STATE OF CALIFORNIA

THE RESOURCES AGENCY DEPARTMENT OF FISH AND GAME

FISH BULLETIN

HISTORY AND STATUS OF STEELHEAD IN CALIFORNIA COASTAL DRAINAGES

SOUTH OF SAN FRANCISCO BAY

by

Robert G. Titus California Department of Fish and Game

Don C. Erman University of California

Emeritus

and

William M. Snider California Department of Fish and Game

Retired

DRAFT MANUSCRIPT AS OF AUGUST 2010

May be cited as: Titus, R. G., D. C. Erman, and W. M. Snider. History and status of steelhead in California coastal

drainages south of San Francisco Bay. In draft for publication as a Department of Fish and Game, Fish Bulletin.

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FOREWORD The drainage-by-drainage accounts in this manuscript are pending revision of steelhead

status designations. Most notably, the “extinct” designation is being replaced by a term which

indicates that, given current habitat conditions, the steelhead life history of coastal rainbow trout

is no longer supported in the stream. In all cases, viable trout habitat still exists in the system,

typically in headwater areas. These areas support the resident life history of coastal rainbow

trout. However, the lack of connectivity between the ocean and these viable spawning and

rearing areas, as a result of habitat alterations, no longer allows anadromy to occur and

noticeably persist. Thus, these populations are not extinct as previously indicated, because the

species still occurs in the stream system, but life history is restricted to the resident type because

of current habitat limitations.

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TABLE OF CONTENTS INTRODUCTION.........................................................................................................................................................8 THE STUDY AREA.....................................................................................................................................................9 MATERIALS AND METHODS ................................................................................................................................10 CALIFORNIA STEELHEAD LIFE HISTORY.........................................................................................................13 DRAINAGE-BY-DRAINAGE ACCOUNTS .............................................................................................................19

SAN MATEO COUNTY........................................................................................................................................19 Ano Nuevo Creek Drainage ...............................................................................................................................19 Cascade Creek Drainage ....................................................................................................................................20 Denniston Creek Drainage .................................................................................................................................20 Frenchman’s Creek Drainage.............................................................................................................................21 Gazos Creek Drainage........................................................................................................................................22

Old Woman’s Creek......................................................................................................................................26 Green Oaks Creek Drainage...............................................................................................................................27 Lobitos Creek Drainage .....................................................................................................................................27 Pescadero Creek Drainage .................................................................................................................................28

Butano Creek and tributaries .........................................................................................................................32 Fall Creek ......................................................................................................................................................35 Little Boulder Creek......................................................................................................................................35 Peters Creek...................................................................................................................................................36

Pilarcitos Creek Drainage...................................................................................................................................36 Arroyo Leon ..................................................................................................................................................36

Pomponio Creek Drainage .................................................................................................................................36 Purisima Creek Drainage ...................................................................................................................................37 San Gregorio Creek Drainage ............................................................................................................................38

Alpine Creek .................................................................................................................................................41 El Corte de Madera Creek and tributaries .....................................................................................................43 Kingston Creek..............................................................................................................................................45 La Honda Creek ............................................................................................................................................45

San Pedro Creek Drainage .................................................................................................................................47 Tunitas Creek Drainage......................................................................................................................................50

East Fork Tunitas Creek ................................................................................................................................51 Whitehouse Creek Drainage...............................................................................................................................51

SANTA CRUZ COUNTY......................................................................................................................................52 Aptos Creek Drainage ........................................................................................................................................52

Bridge Creek .................................................................................................................................................54 Valencia Creek ..............................................................................................................................................55

Arana Gulch Drainage........................................................................................................................................55 Baldwin Creek Drainage ....................................................................................................................................55 Finny Creek Drainage ........................................................................................................................................56 Laguna Creek Drainage......................................................................................................................................56 Liddell Creek Drainage ......................................................................................................................................57 Majors (Coja) Creek Drainage ...........................................................................................................................57 Medler Creek Drainage ......................................................................................................................................59 Pajaro River Drainage, including portions in Monterey, San Benito, and Santa Clara counties ........................59

Corralitos Creek and Tributaries ...................................................................................................................62 Llagas Creek..................................................................................................................................................66 Pacheco Creek ...............................................................................................................................................66 Pescadero Creek ............................................................................................................................................71 San Benito River and tributaries....................................................................................................................71

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Uvas Creek ....................................................................................................................................................71 Respini Creek Drainage .....................................................................................................................................71 San Lorenzo River Drainage ..............................................................................................................................71

Bear Creek and tributaries .............................................................................................................................78 Boulder Creek and tributaries........................................................................................................................79 Branciforte Creek and tributaries ..................................................................................................................81 Clear Creek....................................................................................................................................................83 Fall Creek ......................................................................................................................................................84 Kings Creek...................................................................................................................................................85 Newell Creek.................................................................................................................................................86 Zayante Creek and tributaries........................................................................................................................86

San Vicente Creek Drainage ..............................................................................................................................90 Scott Creek Drainage .........................................................................................................................................92

Big Creek ......................................................................................................................................................96 Little Creek....................................................................................................................................................98 Mill Creek .....................................................................................................................................................98

Soquel Creek Drainage ....................................................................................................................................100 Bates Creek .................................................................................................................................................101 East Branch Soquel Creek ...........................................................................................................................102 Moore’s Gulch.............................................................................................................................................103 West Branch Soquel Creek..........................................................................................................................103

Waddell Creek Drainage ..................................................................................................................................104 Wilder Creek Drainage ....................................................................................................................................108

MONTEREY COUNTY............................................................................................................................................108 Alder Creek Drainage ......................................................................................................................................108 Anderson Canyon Creek Drainage...................................................................................................................109 Big Creek Drainage..........................................................................................................................................109 Big Sur River Drainage ....................................................................................................................................111

Juan Higuera Creek .....................................................................................................................................115 Post Creek ...................................................................................................................................................116

Bixby Creek Drainage......................................................................................................................................117 Carmel River Drainage.....................................................................................................................................118 Doud Creek Drainage.......................................................................................................................................118 Garrapata Creek Drainage................................................................................................................................118

Wildcat Canyon Creek ................................................................................................................................119 Granite Canyon Creek Drainage ......................................................................................................................120 Kirk Creek Drainage ........................................................................................................................................120 Limekiln Creek Drainage .................................................................................................................................120 Little Sur River Drainage .................................................................................................................................121 Malpaso Creek Drainage..................................................................................................................................122 McWay Creek Drainage...................................................................................................................................123 Mill Creek Drainage.........................................................................................................................................123 Partington Creek Drainage ...............................................................................................................................124 Plaskett Creek Drainage ...................................................................................................................................124 Prewitt Creek Drainage ....................................................................................................................................125 Rocky Creek Drainage .....................................................................................................................................126 Salinas River Drainage, Including Portions in San Luis Obispo County .........................................................127

Arroyo Seco and Tributaries........................................................................................................................128 Atascadero Creek ........................................................................................................................................135 Nacimiento River and Tributaries ...............................................................................................................135 Paso Robles Creek and Tributaries..............................................................................................................138 San Antonio River and Tributaries ..............................................................................................................140

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Santa Margarita Creek and Tributaries........................................................................................................143 Salmon Creek Drainage ...................................................................................................................................143 San Jose Creek Drainage..................................................................................................................................144

Williams Canyon Creek ..............................................................................................................................146 Soberanes Creek Drainage ...............................................................................................................................146 Soda Springs Creek Drainage ..........................................................................................................................146 Vicente Creek Drainage ...................................................................................................................................147 Villa Creek Drainage........................................................................................................................................147 Wildcat Creek Drainage...................................................................................................................................148 Wild Cattle Creek Drainage .............................................................................................................................148 Willow Creek Drainage....................................................................................................................................148

SAN LUIS OBISPO COUNTY............................................................................................................................150 Arroyo de la Cruz Drainage .............................................................................................................................150 Arroyo Grande Creek Drainage .......................................................................................................................157

Lopez Canyon Creek and Other Tributaries ................................................................................................159 Cayucos Creek Drainage..................................................................................................................................161 Chorro Creek Drainage ....................................................................................................................................161

Dairy Creek .................................................................................................................................................163 San Bernardo Creek.....................................................................................................................................163 San Luisito Creek ........................................................................................................................................164

Coon Creek Drainage.......................................................................................................................................164 Diablo Canyon Creek Drainage .......................................................................................................................164 Islay Creek Drainage........................................................................................................................................165 Little Pico Creek Drainage...............................................................................................................................165 Morro Creek Drainage .....................................................................................................................................166

Little Morro Creek.......................................................................................................................................168 Old Creek Drainage..........................................................................................................................................168 Pico Creek Drainage ........................................................................................................................................169 Pismo Creek Drainage......................................................................................................................................170 Salinas River Drainage (see Monterey County) ...............................................................................................172 San Carpojo (San Carpoforo) Creek.................................................................................................................172

Estrada Creek ..............................................................................................................................................174 San Luis Obispo Creek Drainage .....................................................................................................................174

Castro Canyon Creek...................................................................................................................................180 Harford Canyon Creek ................................................................................................................................180 Prefumo Creek.............................................................................................................................................181 Reservoir Canyon Creek..............................................................................................................................182 See Canyon Creek .......................................................................................................................................183 Stenner Creek ..............................................................................................................................................184

Ssn Simeon Creek Drainag ..............................................................................................................................187 Steiner Creek ...............................................................................................................................................193

Santa Rosa Creek Drainage..............................................................................................................................193 Toro Creek Drainage........................................................................................................................................203 Villa Creek Drainage........................................................................................................................................207

SANTA BARBARA COUNTY ...........................................................................................................................208 Arroyo Hondo Drainage...................................................................................................................................208 Canada del Corral Drainage .............................................................................................................................208 Canada Honda Creek Drainage ........................................................................................................................208 Carpinteria Creek Drainage..............................................................................................................................209 Dos Pueblos Canyon Creek Drainage ..............................................................................................................209 Gaviota Creek (Canada de la Gaviota) Drainage .............................................................................................209 Mission Creek Drainage...................................................................................................................................209

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Rattlesnake Creek........................................................................................................................................210 Refugio Creek (Canada del Refugio) Drainage................................................................................................210 Rincon Creek Drainage, Including Portinos in Ventura County ......................................................................211 San Antonio Creek Drainage............................................................................................................................211 San Jose Creek Drainage..................................................................................................................................212

Atascadero Creek ........................................................................................................................................212 Santa Maria River Drainage, Including Portions in San Luis Obispo and Ventura Counties...........................212

Cuyama River and tributaries ......................................................................................................................214 Sisquoc River and tributaries.......................................................................................................................215

Santa Ynez River Drainage ..............................................................................................................................216 Agua Caliente Creek ...................................................................................................................................223 Alisal Creek.................................................................................................................................................223 Ballard Creek...............................................................................................................................................223 Cachuma Creek ...........................................................................................................................................223 Gidney Creek...............................................................................................................................................224 Hilton Canyon Creek...................................................................................................................................224 Mono Creek and Tributaries........................................................................................................................224 Salsipuedes Creek and Tributaries ..............................................................................................................225 Santa Cota (Zanja de Cota) Creek ...............................................................................................................226 Santa Cruz Creek and Tributaries................................................................................................................226 Tequepis Canyon Creek ..............................................................................................................................226 Zaca Creek...................................................................................................................................................226

Tecolote Creek Drainage..................................................................................................................................227 VENTURA COUNTY..........................................................................................................................................228

Big Sycamore Canyon Creek Drainage............................................................................................................228 Calleguas Creek Drainage................................................................................................................................228 Santa Clara River Drainage, Including Portions in Los Angeles County.........................................................228

Piru Creek and Tributaries, including Portions of the Creek System in Los Angeles County.....................230 Santa Paula Creek and Tributaries...............................................................................................................231 Sespe Creek and Tributaries ........................................................................................................................232 Minor Mainstem Santa Clara River Tributaries...........................................................................................235 Santa Clara River Headwater Tributaries in Los Angeles County ..............................................................235

Ventura River Drainage ...................................................................................................................................236 Coyote Creek and Tributaries......................................................................................................................239 Matilija Creek and Tributaries.....................................................................................................................240 North Fork Matilija Creek and Tributaries ..................................................................................................240 San Antonio Creek and Tributaries .............................................................................................................241

LOS ANGELES COUNTY ..................................................................................................................................242 Arroyo Sequit Drainage ...................................................................................................................................242 Los Angeles River Drainage ............................................................................................................................242

Arroyo Seco Creek and Tributaries .............................................................................................................243 Big Tujunga Creek and Tributaries .............................................................................................................243 Other Tributaries .........................................................................................................................................243

Malibu Creek Drainage ....................................................................................................................................243 San Gabriel River Drainage .............................................................................................................................246 Topanga Creek Drainage..................................................................................................................................248 Various Smaller Coastal Drainages..................................................................................................................248

ORANGE COUNTY ............................................................................................................................................249 San Juan Creek Drainage .................................................................................................................................249 Santa Ana River Drainage................................................................................................................................250

SAN DIEGO COUNTY and BAJA CALIFORNIA.............................................................................................251 Otay River Drainage ........................................................................................................................................251

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San Diego River Drainage................................................................................................................................251 San Dieguito River Drainge .............................................................................................................................251 San Luis Rey River Drainage...........................................................................................................................252 San Mateo Creek Drainage ..............................................................................................................................252 San Onofre Creek Drainage .............................................................................................................................254 Santa Margarita River Drainage.......................................................................................................................254 Santo Domingo River Drainage .......................................................................................................................255 Sweetwater River Drainage..............................................................................................................................256 Tijuana River Drainage ....................................................................................................................................256

OVERALL TRENDS FROM....................................................................................................................................257 DRAINAGE-BY-DRAINAGE ACCOUNTS ...........................................................................................................257 DISCUSSION............................................................................................................................................................260 RESEARCH AND MANAGEMENT RECOMMENDATIONS..............................................................................265 ACKNOWLEDGMENTS .........................................................................................................................................266 REFERENCES ..........................................................................................................................................................266

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INTRODUCTION Populations of native anadromous salmonids all along the Pacific coast of the continental

U.S. have declined sharply within the last 150 years. Steelhead (Oncorhynchus mykiss irideus,

following Behnke 1992) along the central and southern coast of California have been especially

hard-hit within the last 50 years, primarily because of reductions in the amount and quality of

freshwater habitat. In a partial list of depleted stocks published recently by the American

Fisheries Society (Nehlsen et al. 1991), nine principal steelhead stocks south of San Francisco

Bay were included, six of which were rated as having a high risk of extinction. At least 11 other

stocks were listed as extinct.

The steelhead leads a seemingly tenuous existence under natural conditions in this arid,

southern extent of its range. Stream flows are highly stochastic, and vary greatly both seasonally

and annually. During the dry summer, stream flow often becomes interrupted, especially in the

lower river reaches. Sufficient surficial flow is needed during the winter rainy season to breach

a sandbar which closes the mouth of most of these streams. With a connection provided,

steelhead and other migratory fishes may migrate between marine and fresh water, where

different phases of their life cycles are completed.

In addition to these natural fluctuations in stream flow, a burgeoning human population has

put an even greater demand on already limited freshwater resources. During the past 50 years,

dams and water diversion systems have been built, and groundwater pumping has increased, to

meet the growing human demand for water. Dams block steelhead access to upstream spawning

and rearing areas, and regulate stream flow so that below-dam releases may be very low or

eliminated altogether. Diversions and pumping also remove water from the stream channel, the

effects of which are many from the standpoint of steelhead production. The gross effects include

loss of the migratory corridor between the stream and the ocean, and reduction or complete

elimination of spawning habitat for adults and rearing habitat for juveniles. Virtually every large

coastal river system south of San Francisco Bay has been developed for water extraction, leaving

only some of the smaller streams as more-or-less intact, natural steelhead habitats.

The high priority of maintaining stream flows for anadromous salmonid production in

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California was exemplified by the results of a workshop presented by the California Advisory

Committee on Salmon and Steelhead Trout (Vondracek and Callaham 1987). The workshop was

commissioned to identify researchable questions, and produce a research and development plan

to address these questions, as the first step in formulation of a comprehensive management plan

for California’s declining salmon and steelhead stocks. Among the 12 general topics addressed,

five aspects of water supply needs topped the final list of 18 specific problems given a “critical”

status by both technical experts and resource users.

A recently published compilation of essays (Lufkin 1991) illustrates in lay terms the array of

problems that have led to the precipitous decline of California salmon and steelhead during the

past century or so. One striking trend in both Vondracek and Callaham (1987) and Lufkin

(1991) is the slant toward Central Valley and North Coast salmonid stocks (e.g. see Map 1 in

Lufkin 1991). Overall, relatively little consolidated effort has been expended on determining the

status and factors which affect steelhead stocks south of San Francisco Bay.

The purpose of this paper is to present the historical and current status of steelhead in coastal

California streams south of San Francisco Bay. Habitat conditions, in conjunction with

population information, are used as the means for making assessments. When possible, factors

that regulate population size are identified, both on an interannual basis and with regard to long-

term population trends. In addition, existing biological information is inventoried for future use

in ecologically characterizing these populations. Finally, contemporary theories in both basic

and salmonid ecology are integrated with the results to develop future research ideas.

THE STUDY AREA

The study area consists of the California coastal region from south of San Francisco Bay to

northern Mexico (Fig. 1). Specifically, the California counties of San Mateo, Santa Cruz,

Monterey, San Luis Obispo, Santa Barbara, Ventura, Los Angeles, Orange, and San Diego are

included, as is the northern portion of the Mexican state, Baja California. When appropriate,

headwater tributaries in inner California coastal counties are also included and identified as such.

Although average annual precipitation generally decreases from north to south in the study

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area, a commonality throughout is that most precipitation within any region falls during winter

(Espenshade 1970). Summers are dry during which freshwater discharge from coastal drainages

is greatly reduced and sandbars close the mouths of many streams entering the Pacific Ocean.

Under such conditions, movements of migratory fishes to and from the ocean are blocked until

the first heavy rains of the wet season remove the sandbars. Under extreme drought conditions,

stream channels may essentially be dewatered which results in high levels of mortality of stream

fishes, including juvenile steelhead. Thus, the streams included in the study area are

characterized as being hydrologically unstable, an important factor to consider in an analysis of

steelhead life history patterns.

Another indicator of general climatic conditions in the study area is the vegetation, and like

precipitation, vegetation too generally follows a gradient from north to south (Espenshade 1970).

The coastal drainages in San Mateo and Santa Cruz counties are included in the southernmost

portion of the humid redwood (Sequoia sempervirens) belt, although a narrow strip of coastal

scrub also extends into San Mateo County from its more northerly distribution (Munz 1959).

South of the Pajaro River, which comprises the Santa Cruz/Monterey county line, redwoods only

occur along the lower portion of some streams in central Monterey County (e.g. the Big Sur

River). Otherwise in Monterey County, arid plant communities dominate, such as chaparral, oak

woodland, and grassland. From San Luis Obispo County and southward, arid landscapes are the

norm, including grassland, chaparral, and coastal sage scrub. Shapovalov and Taft (1954),

Cooper et al. (1986), and Woelfel (1991) present descriptions of redwood, chaparral, and coastal

sage scrub/chaparral dominated drainages, respectively, which span the continuum of steelhead

stream types found in the study area.

MATERIALS AND METHODS

Stream-specific information on steelhead in central and southern California was gathered

from three main sources. (i) A literature search was conducted for pertinent journal articles,

California Department of Fish and Game (CDFG) administrative reports and fish bulletins, and

other resource agency, university, and consultant publications. (ii) Resource agency files were

reviewed, especially CDFG stream survey files. (iii) Interviews were conducted with

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professional biologists, academicians, and representatives of sportfishing organizations and other

special interest groups for information from personal files, and anecdotes based on personal

observations.

The information collected was used to construct drainage-by-drainage historical reviews and

current status reports. When available, data were presented to demonstrate actual population

trends and characteristics. Information on the presence and distribution of conspecific resident

rainbow trout (see below) within a drainage was also given when available, as an indication of

the overall presence and distribution of suitable habitat for O. m. irideus, even where steelhead

no longer occur. Information on hatchery operations in the study area was compiled, as were

trout stocking records. The reports were organized by county (from north to south), and then

alphabetically, by drainage system entering the Pacific Ocean within each county, and by main

tributary within each drainage. The information for each stream is generally presented in

chronological order.

Some of the extensive data presented by Shapovalov and Taft (1954) were reanalyzed to

provide a clear and concise summary of their results within the context of contemporary

salmonid ecology. This summary was used as the basis for the forthcoming section, “Life

History Analysis”.

Smith (1982b) and coworkers surveyed 34 Santa Cruz County steelhead streams during late

fall 1981. The density of smolt-sized juvenile steelhead was determined by electrofishing at 1–

10 sites in each stream. These fish were ≥76 mm (3 inches) in standard length and usually age

1+ (see below for technical definitions). Densities reported herein were converted from no.

trout/10 ft of stream channel to no. trout/m. When more than one site was sampled in a stream,

the mean (± SD) density was calculated and reported for that stream. Smith (1982b) also gave

the mean standard length of smolt-sized steelhead at each stream site. Again, when more than

one stream site was sampled, the mean (± SD) of mean standard lengths was calculated and

reported for that stream. The county-wide average in fall 1981 of both density and standard

length of smolt-sized steelhead was calculated (3.8 trout/m and 95.8 mm, respectively), and

actual values presented herein for each stream are compared against these overall averages.

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Statistical analyses, using mostly parametric tests, were made of several other small data sets,

primarily to strengthen the presentation of previous findings. Examples of such analyses were

that of Keegans’s (1990a) data on steelhead habitat use in Malibu Creek (Los Angeles County),

and CDFG data on juvenile steelhead size and growth in the Arroyo de la Cruz (San Luis Obispo

County). Numerous other unpublished data sets contained in CDFG stream survey files, mostly

of fish lengths, were summarized for presentation herein using simple descriptive statistics (e.g.

mean, standard deviation, etc.). Some of these data were also used to produce figures which

illustrate population characteristics, such as juvenile and adult population structure.

All data are reported in metric units. Visual estimates of juvenile trout lengths were rounded

to the nearest 0.5 cm, and those of adults to the nearest cm. Visual estimates of adult weights

were converted to the nearest 0.1 kg. Conversions of both visually estimated and measured trout

densities reflect the measurement scale used in the original report. For example, trout density

estimates were often made on a scale of 100 ft of channel length. These values have been

converted to no. trout/30 m (100 ft = 30.5 m). Fish density reports on a scale of ≤ 10 ft have

been converted to no. trout/m.

The reporting of fish length measurements followed common convention (Bagenal 1978):

standard length (SL), from the tip of the snout to the base of the median caudal (tail) fin rays;

fork length (FL), from the tip of the snout to the fork in the caudal fin; and total length (TL),

from the tip of the snout to the end of the longest lobe of the caudal fin. Visually estimated

lengths, and lengths not specified otherwise, were presumed to approximate total lengths.

Age-classes were designated as age 0+ for young-of-the-year, 1+ for 1-year-olds (also called

yearlings), 2+ for 2-year-olds, etc., using the approximate period of hatching (late winter–spring)

as the birth date. The ‘+’ sign indicates growth beyond the birth date, and is typically used for

fish sampled during summer–winter. The ages of steelhead that have returned from the ocean

were designated as A/B, where A and B are the number of years spent in fresh and salt water,

respectively, and are additive to give the total age of the fish.

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CALIFORNIA STEELHEAD LIFE HISTORY

The coastal rainbow trout, O. m. irideus, is a polymorphic subspecies (Behnke 1992).

Populations may be anadromous (sea-run), resident, or mixtures where the two forms

presumably interbreed. Although they comprise the same subspecies, the different forms have

unique common names: the anadromous form is called steelhead; the resident form is simply

called rainbow trout. Both forms may exist in the same stream system, and in some instances

may be physically discrete from one another due to an impassable barrier to upstream migration,

such as a waterfall. In these situations, rainbow trout occur above the barrier, and steelhead, or a

mixed morph population, exist below.

In polymorphic salmonids, males exhibit an especially high degree of life history variation.

The literature is replete with examples which demonstrate that, relative to females, males mature

at an earlier age and smaller size on average. This variation is particularly striking in

anadromous salmonids where males often mature as parr prior to migration to the sea. In some

cases, mature male parr1 may have a relatively high probability of remaining in fresh water and

functionally assuming a resident life style (e.g. Dellefors and Faremo 1988; Hansen et al. 1989).

In other instances, most mature male parr eventually migrate to the sea following spawning (e.g.

Titus and Mosegaard 1992) and return following a growth period as much larger migrant

spawners (H. Mosegaard and R. Titus, Institute of Limnology, Uppsala University, Uppsala,

Sweden, unpubl. data). So, in iteroparous anadromous salmonids (i.e. those which spawn more

than once) such as steelhead, brown trout (Salmo trutta), Atlantic salmon (S. salar), and Arctic

charr (Salvelinus alpinus), males are able to spawn several times during their lifetime, beginning

potentially as parr (often age 1+) and continuing as large migrants that return from the ocean to

spawn. This general life-history plasticity in males results in higher age-specific mortality rates

for males than females because they begin breeding at an earlier age (e.g. Shapovalov and Taft

1Although these fish have been referred to as “precocious males” for many years, this term inadvertently and inaccurately

suggests that this life history pattern is an abnormality. The preferred contemporary terminology is instead “mature male

parr” (J. E. Thorpe, Freshwater Fisheries Laboratory, Pitlochry, Scotland, pers. comm.).

14

1954; see below). Interestingly, even in typically semelparous anadromous salmonids (i.e. those

which spawn once and die) such as chinook salmon (O. tshawytscha), mature male parr are

anomalous in that they survive after spawning (Robertson 1957).

Trends in specific life history characters among populations of anadromous salmonids have

also been detected. For example, mean smolt age and size of Atlantic salmon and anadromous

brown trout generally increase as a function of increasing latitude (Fahy 1978; L’Abée-Lund et

al. 1989; Metcalfe and Thorpe 1990). Much of this variation is explained by an index of growth

opportunity which integrates two primary growth regulating factors in fishes, light and

temperature (reviewed by Thorpe 1990). Another environmental factor which may be important

in the selection of life history traits in anadromous salmonids is hydrological stability, especially

in small streams (Borgstrøm and Heggenes 1988; Titus and Mosegaard 1989, 1992).

Geographic variation in steelhead life-history traits has been studied in much less detail,

although Withler (1966) presented data for six coastal locations from central California to

southern British Columbia. In contrast to Atlantic salmon and brown trout, mean smolt age of

steelhead did not vary clinally with latitude (Fig. 2a; r2 = 0.04, p = 0.72). However, mean sea

age at maturity (Fig. 2a; r2 = 0.50, p = 0.11) and mean adult length (Fig. 2b; r2 = 0.96, p<0.01)

clearly increased with increasing latitude, despite the small sample size (data adapted from

Withler 1966).

Within- and between-population variation in life history traits is not well documented for

California steelhead, especially south of San Francisco Bay where environmental conditions

follow a sharp gradient. Yet, Shapovalov and Taft’s (1954) comprehensive life history study

was conducted within this area, namely at Waddell Creek in Santa Cruz County. For use as a

general reference with which comparisons may be made, the following is a summary and

analysis of several key life history characteristics from Shapovalov and Taft’s (1954) landmark

study, except as otherwise noted.

South of San Francisco Bay, steelhead are all winter-run fish. Entry into freshwater is

dependent upon breaching of the sandbar at the stream mouth following the onset of the winter

rainy season. At Waddell Creek, the upstream spawning migration was rather protracted and

15

varied among years (Fig. 3a; see also Fig. 23 in Shapovalov and Taft). On average, most

upstream movement occurred during December–April. Males dominated numerically in the

early portion of the run.

Steelhead life histories were highly variable at Waddell Creek. Yet, of 32 observed life

histories, four categories were dominant: 2/1 (29.8%), 2/2 (26.5%), 3/1 (10.5%), and 2/1S.1

(8.1%). All other categories comprised less than 5% of the run each. So, most migrant spawners

were total ages 3 (35%) and 4 (46%), and maximum age was 7 (Fig. 4). Overall, the run

consisted of 82.8% first-time spawners, and 17.2% repeat spawners among which 15.0% were

second spawners, 2.1% were third, and 0.1% were fourth spawners.

The mean smolt age of males (2.08 yr; calculated as in Fahy 1978) was only slightly lower

than that of females (2.15 yr), although based on the frequency distribution of smolt ages for

each sex (Fig. 5a), this difference was significant (χ² = 13.965, DF = 3, p<0.003; data from Table

28 in Shapovalov and Taft 1954). The mean smolt age for both sexes combined was 2.12 yr.

The mean sea age of males spawning for the first time was 1.31 yr, while that for females

was 1.55 yr (calculated as in Fahy 1978). Based on the frequency distribution of sea ages for

each sex (Fig. 5b), this difference was highly significant (χ² = 190.392, DF = 2, p<0.0001; data

from Table 28 in Shapovalov and Taft 1954). The mean sea age for both sexes combined was

1.43 yr.

Overall, the mean total age of male migrant spawners was 3.51 yr, while that for females was

3.91 yr (calculated as for mean smolt age). Based on the frequency distribution of total ages for

each sex (Fig. 4), this difference was highly significant (χ² = 233.645, DF = 5, p<0.0001; data

from Table 28 in Shapovalov and Taft 1954). Age-specific mortality rates were higher for males

than females, as evidenced by (i) the lower average age of males; and (ii) the increase in the ratio

of migrant females:migrant males with spawning experience, such that the sex ratio among first

spawners was 1.06 females:1 male, among second spawners was 1.44 females:1 male, among

third spawners was 3.71 females:1 male, and fourth-spawning females (n = 5) had no fourth-

spawning male mates (data from Table 28 in Shapovalov and Taft 1954). Note, however, that

the sex ratio in the estimated total run averaged 1.06 females:1 male (SD = 0.12) over the years,

16

and there was no significant trend in sex ratio over time (r2 = 0.12, p>0.35; data from Table 35 in

Shapovalov and Taft 1954).

Mean fork lengths of migrant males among all life history categories ranged from 38.5 to

79.5 cm, the mean of weighted means being 54.8 cm. Corresponding lengths of migrant females

ranged from 40.2 to 80.5 cm, with a mean of weighted means of 61.4 cm. The mean of weighted

mean fork lengths for both sexes combined was 58.3 cm (data from Table 32 in Shapovalov and

Taft 1954).

Thus, relative to females on average, males smolted and migrated to the ocean at a slightly

earlier age, matured and began breeding at an earlier sea age, were smaller in length at spawning,

and had a shorter life span.

On the spawning grounds, the female dug a redd (gravel nest) at the tail of a pool, typically

where current velocity increased at the head of a downstream riffle. Little basic research has

been done on steelhead mating systems, although Needham and Taft (1934) described one

spawning aggregation from Waddell Creek in detail (summarized also in Shapovalov and Taft

1954). A large migrant female was accompanied by one similarly sized migrant male; four

smaller subordinate migrant males; and two mature male parr, 15–23 cm in length (in total, 7

males:1 female) (c.f. Campbell 1977; Maekawa and Onozato 1986; Titus and Mosegaard 1992

on the composition of spawning aggregations in other polymorphic salmonids). In addition to a

dominant migrant male, subordinate migrant males and mature male parr also participate in

spawning by adopting a “sneaking” behavior. The proportion of eggs fertilized by mature male

parr can be substantial (Maekawa and Onozato 1986; Hutchings and Myers 1988; Jordan and

Youngson 1992), and even in the absence of a migrant male, mature male parr successfully mate

with a large migrant female (Shapovalov and Taft 1954; Maekawa and Onozato 1986; Myers

and Hutchings 1987).

As with the upstream spawning migration, the downstream migration of spent adult steelhead

was also protracted and variable among years (Fig. 3b). On average, most downstream

movement occurred during March–July. Fish which did not return to the ocean immediately

after spawning held in larger pools.

17

The development rate of steelhead eggs is dependent upon water temperature in the gravel.

Based on the results of Wales (1941), hatching occurs after about 19 d at an average temperature

of 15.5° C (295 degree-days), and 80 d at about 4.5° C (360 degree-days). Shapovalov and Taft

(1954) estimated that hatching time in Waddell Creek was from 25 to 35 d, emergence from the

gravel began 2–3 weeks after hatching, and another 2–3 weeks was required to complete

emergence. Mortality rates of salmonid fry are typically high following emergence (reviewed by

Titus 1990), and age 0+ steelhead utilize habitats with swift currents, moving gradually into

deeper water as they grow (Shapovalov and Taft 1954).

Downstream migrants captured in the trap at Waddell Creek (Shapovalov and Taft 1954)

comprised five age-classes, 0+ to 4+, in the following proportions, respectively: 0.40, 0.40, 0.19,

0.01, and a negligible proportion of 4+ fish (0.04% of the total number of fish passed through the

trap for all years combined). Steelhead moved downstream essentially during all months of the

year, but the main migrations were in the spring and summer, with the oldest fish appearing in

the trap first: 92% of age 2+ and 3+ fish during March–May; 68% of age 1+ fish during April–

June, with a secondary migration (26%) during October–early January; 73% of age 0+ fish

during June–July, and an additional 20% during August–September (Fig. 6a). Variation in the

time of downstream migration was apparently related to interannual differences in precipitation

and thus stream flow and water temperature.

Because the trap was situated well above the mouth of Waddell Creek (2.2–2.8 km, the

location of the mouth depending upon the amount of freshwater outflow and oceanic conditions),

downstream movement was not necessarily always equivalent with smolt emigration. Indeed,

Shapovalov and Taft (1954) found from returns of marked first spawners, that the proportion of

marked fish which had entered the ocean in the same year of their initial downstream migration,

relative to those which entered the ocean the following year, was only about 0.08 for age 1+

migrants, but increased to 0.90 and 0.69 for 2+ and 3+ migrants, respectively (see Table 71 in

Shapovalov and Taft 1954). So, functionally, the downstream movements of different age-

classes, or individuals within age-classes, were probably associated with a variety of behaviors

or population processes. For example, the downstream movement of 0+ trout may have resulted

18

from the dispersal of emergent fry clusters during the period of intense population regulation in

the early free-swimming stage. Movement of 1+ trout may have primarily reflected an

ontogenetic habitat shift to deeper water in the lower stream and lagoon, in addition to seaward

migration of smolts. The majority of 2+ and 3+ trout were apparently smolts on their way to the

ocean.

The total number of upstream migrants (3,104) captured in the trap was small, relative to the

total number of trapped downstream migrants (36,779; data for all years combined). Thus, most

trout which moved downstream either remained in the lower stream or lagoon, migrated to the

ocean, or died. Among upstream migrants, only 1% were age 0+, 29% were age 1+, 53% were

age 2+, 15% were age 3+, and 2% were age 4+. Overall, 80% of upstream movement occurred

during December–January, for all age-classes and years combined (Fig. 6b). Shapovalov and

Taft (1954) observed that many upstream migrants were sexually mature. These mature trout

were probably moving upstream to spawn, along with migrant spawners returning from the

ocean.

Shapovalov and Taft (1954) knew little about the ocean migrations of California steelhead,

with few being captured at sea by commercial salmon trollers. This knowledge gap continues to

exist for the most part. Tagged individuals from more northerly stocks of North American

steelhead have been recovered on the high seas as far west as 42° 44'N, 163° 32'E, and as far

south as 40° 58'N, 159° 39'W (Burgner et al. 1992). Although based on few data, California

steelhead may make more restricted westward migrations than more northerly stocks.

Shapovalov and Taft (1954) did determine, however, that homing rates of marked steelhead at

Waddell Creek and nearby Scott Creek were very high; 98.1% and 97.1%, respectively (see also

Taft and Shapovalov 1938).

Estimated survival of Waddell Creek steelhead, from eggs to first spawning adults, ranged

from 0.017% to 0.029%, and averaged 0.023% (SD = 0.005%, n = 5; see Table 58 in Shapovalov

and Taft 1954). There was a strong negative correlation (r2 = 0.88, p<0.02) between the number

of first spawners recruited and the number of eggs laid at the start of the life cycle (Fig. 7).

Thus, observed recruitment was negative density-dependent in relation to egg production. Of

19

course, to consider this apparent functional relationship as true, one must assume that oceanic

conditions and angling had relatively constant effects on survival to first spawning.

Survival of all age-classes of marked Waddell Creek steelhead, from time of downstream

migration to first spawning, ranged from 1.7% to 6.0%, and averaged 3.5% (SD = 1.8%, n = 5;

see Table 75 in Shapovalov and Taft 1954). For all age-classes and years combined, 383 first

spawner adults returned from 12,679 downstream migrants marked at the trap, for an overall

survival of 3.0%. Furthermore, there was a strong positive correlation (r2 = 0.86, p<0.02)

between the age at which steelhead made their initial downstream migration and were marked at

the trap, and the proportion of fish in each age-class surviving to return from the ocean as first

spawners (Fig. 8). If it is assumed that fish size is directly proportional to age, then survival

increased with size as well. However, these relationships are confounded by the fact that the

various age/size-classes would not be experiencing the same potential mortality factors

simultaneously through time because of their differing, age-class specific life histories,

especially with regard to the proportion of each age-class entering the ocean in any given year

(see above). To fully evaluate age-class specific survival of downstream migrants to first

spawning, mortality rates would have to be determined for each age-class for both the remainder

of their freshwater period, as well as in the ocean.

DRAINAGE-BY-DRAINAGE ACCOUNTS

SAN MATEO COUNTY

Ano Nuevo Creek Drainage Although no detailed historical information was discovered for Ano Nuevo Creek,

Shapovalov and Taft (1954, p. 201) mentioned that the stream supported a very small steelhead

run, relative to the runs observed at Scott and Waddell creeks during the 1930’s–40’s. Juvenile

steelhead were observed in the creek as recently as 1992 (J. Nelson, CDFG, pers. comm.).

20

Cascade Creek Drainage No juvenile steelhead/rainbow trout, or any other fishes, were observed in Cascade Creek

when surveyed by the CDFG on 20 July 1978. However, a local resident reported the former

presence of “trout” in the 5 km long creek. Several agricultural diversion dams throughout the

stream created complete migration barriers and reduced stream flow. The stream bottom was

heavily silted as a result of agriculture, grazing, and road crossings. Overall, Cascade Creek did

not provide habitat conditions conducive to steelhead/rainbow trout production.

Denniston Creek Drainage Denniston Creek is a short-run tributary to Half Moon Bay. In a 1941 listing, the CDFG

(unpubl. file document of 26 April 1941) described Denniston Creek as having a fair year-round

flow, a small lagoon which opened and closed throughout the summer, known steelhead and

coho salmon spawning migrations, fair summer trout fishing, and water used for irrigation.

By 1953, a small dam had been built on the creek about 1.6 km above the mouth. The CDFG

maintained a catchable rainbow trout fishery in the impoundment during 1953, but it was

discontinued in 1954 because of private property access restrictions (CDFG, unpubl. field notes

of 26 February 1953–29 March 1955). The dam presumably blocked upstream migration of

adult steelhead at that time.

The CDFG conducted a cursory electrofishing survey at Denniston Creek on 21 October

1974 (W. E. Strohschein, CDFG, unpubl. memo. of 28 October 1974). Access to the stream was

limited because of dense riparian vegetation. In a 4.6 m section about 0.6 km above the dam,

four juvenile steelhead/rainbow trout were captured that averaged 78 ± 19 mm FL (range, 61–99

mm FL). In a 9 m section about 0.2 km above Highway 1, two young-of-the-year steelhead were

captured, both about 64 mm FL. The spillway from the dam appeared to be an impassable

barrier to upstream migrants. Stream flow was continuous above the dam but nearly interrupted

below because of a water diversion.

The lowermost 4.8 km of Denniston Creek was surveyed by the CDFG on 20 April 1992.

The stream was heavily overgrown with riparian vegetation. Adjacent soils were highly erosive

21

and sand dominated the stream substrate. Areas with spawning gravel were small, patchy, and

highly embedded or compacted. Small shallow pools with heavy cover provided adequate

rearing habitat for young-of-the-year steelhead. The dam was still a migration barrier, as was a

1.8 m culvert located about 0.8 km above the dam. One water diversion was seen upstream from

the culvert. Juvenile steelhead/rainbow trout, 10–15 cm in length, were seen in pools throughout

the stream. Presumably, those above the dam were resident trout.

Frenchman’s Creek Drainage Frenchman’s Creek, which enters the Pacific Ocean near the community of Half Moon Bay,

was surveyed by the CDFG during the mid-1930’s. Juvenile steelhead were present and natural

propagation was rated as fair. Small irrigation diversion dams were present, but they were not

thought to be barriers to steelhead migration. The stream was fished lightly. The population was

supplemented with 10,000 juvenile steelhead in 1930, and 8,000 in 1932.

The creek was not surveyed again by the CDFG until 25 September 1958. Due to a high

amount of sand in the stream bottom, salmonid spawning areas were poor in the lowermost 4.8

km of stream, and poor to fair in the next 3.2 km upstream. Rearing habitat, in the form of pools,

undercut banks, and vegetative cover, was apparently abundant throughout. Temporary dams

were noted, from which several diversions were made. Steelhead reportedly used the stream for

spawning, but juveniles were not seen due to low water clarity. Streamside erosion was noted as

a problem. Private landowners had apparently stocked brown trout in the upper canyon portion

of the stream some years before the survey. Overall, Frenchman’s Creek was rated as a minor

steelhead stream.

In a CDFG electrofishing survey in October 1974 (W. E. Strohschein, CDFG, unpubl. memo.

of 1 November 1974), two juvenile steelhead/rainbow trout (15–18 cm FL) and a brown trout

(27 cm FL) were captured in a short stream section immediately downstream from the Highway

1 bridge. In a 15 m section in the upper stream, eight juvenile steelhead/rainbow trout were

captured which averaged 7.9 cm FL (range, 6.4–10.4 cm). Two brown trout, 18.8 and 19.3 cm

FL, were also captured.

22

The CDFG surveyed the lowermost 5.5 km of Frenchman’s Creek on 19–20 September

1979. Salmonid spawning and rearing habitat were apparently much the same as in the 1958

survey (see above). Three flashboard dams, 0.9–2.4 m high, were noted as potential barriers to

fish migration. Five active water diversions were identified. Age 0+ salmonids were observed

throughout the survey area. Electrofishing samples were taken in two reaches which totalled

about 366 m (L. Fish and I. L. Paulsen, CDFG, unpubl. memo. of 23 October 1979). A total of

63 juvenile steelhead (mean FL = 9.7 cm; range, 6.4–20.3 cm) and 14 brown trout (mean FL =

11.4 cm; range, 7.9–22.9 cm) were captured. Among the steelhead, three age-classes (0+, 1+,

and ≥ 2+) were apparent with corresponding mean fork lengths of 8.4, 15.7, and 19.6 cm,

respectively. Age 0+ fish comprised 84% of the total steelhead catch.

In subsequent environmental documents contained in the CDFG file, it was noted that since

1971, water use in the drainage had increased and cumulative effects posed a direct threat to

fishery resources.

Locks Creek is the principal tributary to Frenchman’s Creek, but no information was

available regarding the stream or its status as a steelhead production area.

Gazos Creek Drainage Gazos Creek was surveyed by the CDFG in 1934. Spawning grounds were abundant, no

barriers or diversions were noted, and steelhead were present. The stream was apparently

heavily fished by local residents. Early CDFG stocking records showed that the population was

supplemented with 12,000 juvenile steelhead in 1930; 16,000 in 1931; 12,000 in 1932; 12,000 in

1933; 10,000 in 1934; 15,000 in 1935; 15,000 in 1936; 20,000 (@ 917–1,270/kg) in 1938; and

7,000 (@ 2,116/kg) in 1939, for a grand total of 119,000 fish.

The stream was surveyed again by the CDFG in July 1964, from the mouth to headwaters for

a distance of 13 km. Suitable gravels for salmonid spawning were ample, and comprised an

estimated streambed area of about 20,000 m2. Salmonid rearing habitat was also abundant and

apparently of high quality. Many partial and complete barriers to fish migration were observed,

and one diversion in the lower stream stopped all stream flow and fish passage to the ocean.

23

Siltation in the stream, from an adjacent road and past logging, was occurring. Juvenile

steelhead occurred in visually estimated densities of 50 fish/30 m in the lower stream, and 5

fish/30 m in the headwaters. Lengths were 2.5–15 cm, averaging about 5 cm. One 56 cm adult

male steelhead was seen. Natural spawning success was rated as good. Catchable rainbow trout

were planted in the stream at the time of this survey, which resulted in heavy angling pressure on

2-year-old steelhead. Coho salmon also used Gazos Creek.

A sample of juvenile steelhead taken by the CDFG on 28 February 1970 comprised 36 fish

which ranged in fork length from 79 to 165 mm, and averaged 128 mm (SD = 26 mm).

The CDFG conducted several electrofishing surveys during the 1970’s–80’s which provided

at least cursory information on the natural variation in the size/age structure of the juvenile

steelhead population in Gazos Creek. On 21 October 1974 (K. R. Anderson, CDFG, unpubl.

memo. of 28 October 1974), 59 steelhead were captured in a single sweep through a 305 m reach

of stream, about 0.3 km upstream from the Highway 1 bridge. Age 0+ fish comprised 93% of

the catch, and averaged 91 mm FL (range, 71–132 mm FL). The remaining four steelhead were

age 1+ and averaged 155 mm FL (range, 150–165 mm FL).

On 13 October 1975 (G. G. Scoppettone, CDFG, unpubl. memo. of 3 February 1976), 28

juvenile steelhead were captured in a single sweep through a 46 m reach adjacent to the

Campbell Soup Co. diversion. Again, fish ranging in fork length from 38 to 127 mm (mean, 86

mm FL) made up 96% of the catch. Only one clearly older individual was captured, which was

203 mm FL.

During the winter of 1975-1976, entry of adults from the ocean and their migration to

upstream spawning grounds were apparently restricted due to a lack of precipitation and thus

reduced stream flow. No adult steelhead were observed at three sites on Gazos Creek on 2

March 1976 even though the stream was open to the ocean (G. Scoppettone, CDFG, unpubl.

memo. of 19 April 1976).

Salmonids, probably juvenile steelhead, were observed, but not captured, upstream from the

Campbell diversion on 10 August 1976 (M. Cogger, CDFG, unpubl. memo. of 30 August 1976).

24

On 30 May and 15 June 1978, the CDFG surveyed Gazos Creek from the headwaters to the

mouth at the Pacific Ocean. Spawning and rearing habitats for salmonids were still abundant

and of very high quality. Juvenile steelhead were abundant. Most fish were young-of-the-year

averaging about 4 cm, although some trout were up to 20 cm long. Many potential migration

barriers were noted, mostly in the form of woody debris and log jams as the result of prior

logging operations. Siltation and water diversion had a negative impact on salmonid habitat in

the lowermost portion of the stream. It was also noted that 4,000–5,000 catchable rainbow trout

had been planted in Gazos Creek annually during 1960–73.

Two very small samples were taken by electrofishing at Gazos Creek on 8 August 1978 (S.

G. Torres and I. L. Paulsen, CDFG, unpubl. memo. of 17 August 1978). In an upstream section,

8 steelhead were captured which averaged 64 mm FL (range, 46–79 mm FL). Near the Muzzi

diversion site, 4 steelhead were captured which averaged 89 mm FL (range, 69–104 mm FL).

Many more salmonids escaped capture in the sample sections due to equipment failure.

On 27 September 1979, 59 steelhead averaging 86 mm FL (range, 53–160 mm FL) were

captured during a single electrofishing pass in two reaches totaling 236 m near the Muzzi and

Campbell diversions (L. Fish and I. L. Paulsen, CDFG, unpubl. memo. of 23 October 1979). In

a 69 m reach upstream of stream km 3.7, 46 steelhead were captured which had a mean fork

length of 74 mm (range, 46–178 mm FL). Based on the composite of the above samples, three

age-classes of steelhead were apparent: 0+ which averaged 71 mm FL (range, 46–102 mm; n =

85), 1+ which averaged 124 mm FL (range, 107–160 mm; n = 19), and a single, older 178 mm

individual.

No adult steelhead or coho salmon were observed during fish count surveys made on six

occasions from late November 1979 through late April 1980 (K. R. Anderson, CDFG, unpubl.

memo. of 14 July 1980). It was concluded that anadromous salmonid resources had greatly

declined in Gazos Creek.

Logjams were removed in Gazos Creek during July 1980 (D. Eimoto, CDFG, unpubl. memo.

of 5 August 1980). Juvenile salmonids were observed in the stream at that time. The CDFG

also electrofished two reaches for a total of 213 m on 5 September 1980 (P. Walkup, CDFG,

25

unpubl. memo. of 18 September 1980). Age 0+ steelhead averaged 71 mm FL (range, 48–97

mm FL; n = 113 or 88% of the catch), 1+ steelhead averaged 114 mm FL (range, 102–140 mm

FL; n = 14), and ≥ 2+ steelhead averaged 260 mm FL (range, 236–284 mm FL; n = 2). Thus,

despite the absence of adult sightings during the 1979–80 spawning season, at least some

spawning and recruitment did indeed occur.

On 7 September 1984, the CDFG surveyed 8 km of Gazos Creek, beginning at the mouth of

Old Woman’s Creek and working upstream. High quality spawning and rearing habitats for

salmonids were still present, yet very few juvenile steelhead were seen. Those observed were 5–

15 cm TL. Siltation persisted as a problem in the lower stream, and logjams and a landslide

created potential migration barriers. Water continued to be diverted from the stream at several

locations.

The CDFG electrofished two reaches of Gazos Creek on 12 September 1985 (F. Gray,

CDFG, unpubl. memo. of 15 October 1985). In a 61 m reach about 2.4 km upstream from the

mouth, 76 steelhead were captured which ranged in fork length from 38 to 130 mm and averaged

68 mm. In a 91 m reach about 3.2 km above the mouth, 84 steelhead averaged 69 mm FL and

ranged from 45 to 142 mm FL.

In August 1992, Smith (1992) electrofished two reaches totalling 84 m in the lowermost 3.2

km of Gazos Creek. Only pools and glides were sampled. A total of 112 juvenile

steelhead/rainbow trout was captured; 67% of the catch was age 0+ and 33% was age 1+. Ages

were assigned based on length-frequency distributions.

During 12–16 January 1994, Smith (1994) resampled the two reaches in lower Gazos Creek,

and added two reaches between 5 and 7 km above Highway 1. Again, only pools and glides

were sampled. Both age 0+ and 1+ steelhead occurred in all four reaches. Of the 165 juvenile

steelhead captured, 72% were age 0+ and 28% were age 1+ that occurred at mean ± SD

densities of 95 ± 52 trout/100 m and 30 ± 10 trout/100 m, respectively. Overall, juvenile

steelhead population structure in pools and glides was stable between August 1992 and January

1994. In 1993, Nelson (1994c) inventoried the stream habitat in the lowermost 10.5 km of Gazos

Creek, and monitored juvenile steelhead emigration. The detailed habitat typing effort

26

corroborated earlier observations that spawning and rearing habitats were adequate for

maintaining the steelhead population. However, siltation continued to degrade habitat quality by

armoring spawning gravel and filling in pools. During the May–June 1993 survey period, water

quality in the upper stream area (SKM 10) was also degraded by suspended sediment. Signs of

chemical pollution were seen in the lowermost 1.6 km of the creek, although these were not fully

investigated. A well field and surface diversion in the lower creek decreased stream flow during

late summer–early fall, which presumably reduced rearing habitat quantity and quality. There

were 28 logjams in the survey area, seven of which were potential migration barriers except

under very high flow conditions.

Emigrating juvenile steelhead were monitored by use of a downstream migrant trap. The

trap was located just upstream from the well field at about SKM 0.5, and was fished from 29

March 1993 to 1 June 1993. Only 25 steelhead parr and 29 smolts were captured during the nine

weeks of trapping. Peak catches (40% of parr, 34% of smolts) occurred during the week of 26

April 1993. Captured parr averaged 97 mm FL (range, 52–153 mm FL), while smolts averaged

151 mm FL (range, 104–178 mm FL). The low catches suggested a small population, although

more emigration may have occurred prior to the trapping period.

Old Woman’s Creek

Old Woman’s Creek was surveyed from its mouth to headwaters by the CDFG on 23 July

1964. The stream contained suitable spawning and rearing habitat for steelhead. One potential

migration barrier was noted, but no diversions were seen. Juvenile steelhead and coho salmon,

5–15 cm long, were observed at a total estimated abundance of ≤ 500 for the entire stream. One

spawned-out adult female steelhead was seen as well.

In 1993, Nelson (1994c) inventoried the stream habitat in the lowermost 1.2 km of Old

Woman’s Creek. An elevated culvert created a likely migration barrier to upstream migrants,

and the creek was not surveyed above this point. Rearing pools and spawning beds were silted,

and the creek contained logjams that created potential migration barriers. Despite what appeared

to be relatively poor habitat, juvenile steelhead/rainbow trout were seen throughout the survey

27

reach.

STATUS: Nelson (1994c) described the Gazos Creek steelhead population as viable but

declining. This assessment was consistent with observed reductions in habitat quality, quantity,

and access due to siltation, water diversions, and logjams.

Green Oaks Creek Drainage No juvenile steelhead/rainbow trout, or any other fishes, were observed in Cascade Creek

when surveyed from its mouth to headwaters (6 km) by the CDFG on 10 August 1978. Five

dams located throughout the stream created complete migration barriers. There were five

agricultural diversion pumps. Reservoirs in the lowermost 3 km obscured the structure and

function of the natural stream channel. No suitable spawning areas for steelhead were observed.

A local resident reported that reservoirs on the creek were stocked with rainbow trout. Overall,

Green Oaks Creek did not provide habitat conditions conducive to steelhead/rainbow trout

production.

Lobitos Creek Drainage Early CDFG records showed that the Lobitos Creek steelhead population was supplemented

with 8,000 juveniles in 1930 and 14,000 in 1932. In a mid-1930’s CDFG stream survey, the

creek was described as having intermittent summer flow and scattered spawning grounds for

steelhead, and that natural propagation of steelhead had been limited, presumably because of

limited spawning and rearing habitat. The adult steelhead population was lightly fished. Several

“large” steelhead were apparently caught at Lobitos Creek on 25 May 1939 (L. Shapovalov,

CDFG, unpubl. file note).

The CDFG surveyed Lobitos Creek on 24 June 1975, from its headwaters to the mouth at the

Pacific Ocean, for a distance of 4 km. Spawning substrate was rated as poor to fair, with patches

of suitable gravel scattered throughout the survey area. Silt cemented the substrate in some areas

of the stream, especially near the headwaters where logging operations were underway. Rearing

habitat in the form of pools and cover was rated as fair to good. Several potential barriers to fish

migration were noted, including logjams, culverts, small dams, and a natural 1.8 m bedrock

28

waterfall downstream from Highway 1. Several small diversions were identified. Juvenile

steelhead and/or rainbow trout, 2.5–15 cm in total length, were observed throughout the survey

area, although trout density was relatively low above the natural bedrock waterfall in the lower

stream, and much higher in the 0.3 km of stream below the fall where access by migratory trout

was unobstructed. Overall, the stream was underutilized by steelhead, primarily because of fish

passage problems, and it was recommended that future water applications be protested because

of the limited water resources in this small stream drainage. Several such applications, contained

in the CDFG files, were submitted during the late 1970’s.

During the winter of 1975-1976, entry of adults from the ocean and their migration to

upstream spawning grounds were apparently restricted due to a lack of precipitation and thus

reduced stream flow. The mouth at Lobitos Creek did not open, even following rainfall events

during mid–February to early March 1976, and no adult steelhead were observed in the stream

(G. Scoppettone, CDFG, unpubl. memo of 25 March 1976 and 19 April 1976).

Pescadero Creek Drainage Historically, the Pescadero Creek system has supported the largest steelhead population and

fishery in San Mateo County. During the mid-1970’s, the size of the annual adult steelhead run

was estimated at 1,500 fish of which about 400 were harvested in the sport fishery each year

(Elliott 1975). The system undoubtedly supported many more steelhead, and coho salmon as

well, before any major exploitation of the stream drainage began. For example, in 1870 a

commercial fishery existed where a wagon load of steelhead and coho weighing 1–14 kg each

was taken daily from Pescadero Creek between October and March (Skinner 1962). Degradation

of the system was already underway at that time, however, due to the effects of logging, saw

mills, and flour mills. So, it is reasonable to assume that the anadromous fish populations were

previously even larger than the ones which supported the commercial fishery in 1870.

The modern chronicle charting the Pescadero steelhead population begins with early CDFG

records. The upper creek was surveyed by the CDFG on 7 August 1962, from its headwaters to

Portola State Park for a distance of 2.7 km. There were suitable spawning areas for steelhead

29

and rainbow trout in the headwaters and from 0.8 km above Oil Creek to the state park. The

remainder of this portion of the creek was heavily silted, and thus unsuitable for salmonid

spawning. Rearing habitat, in the form of pools and shelter, was adequate for young trout.

Three low-flow migration barriers and one diversion were identified, and the Santa Cruz Lumber

Company was indicated as a pollution source in the stream. Juvenile steelhead and/or rainbow

trout occurred in visually estimated densities of 10–275 trout/30 m (average, 110 trout/30 m),

and were 2.5–18 cm long (average, 5 cm). At that time, the CDFG stocked catchable rainbow

trout in the creek from Portola State Park to San Mateo County Memorial Park to support the

summer trout fishery.

On 8 August 1963, the CDFG surveyed the lowermost 17.5 km of the stream, from the

mouth to Memorial Park. The uppermost 3.5 km of the survey area contained an estimated 3,479

m2 of suitable spawning grounds. Much of the remaining 14 km of streambed in the survey area

was heavily silted and contained only an estimated 1,254 m2 of utilizable spawning substrate for

steelhead. Local residents reportedly observed steelhead spawning near the community of

Pescadero during the 1962-63 season. Pools and shelter provided adequate rearing habitat for

juvenile steelhead. No migration barriers were noted, but 35–50 diversions were observed along

12.9 km of stream, with most of the water being used in agriculture. Siltation was noted as a

major pollution problem in this portion of the stream as well. The density of juvenile steelhead

and/or rainbow trout was estimated at 300 trout/30 m in the upper 6.4 km of the survey area, and

100 trout/30 m in the 11.1 km below (overall average, 175 trout/30 m). The average trout length

was estimated at 7.5 cm with a range of 5–30.5 cm. Steelhead production was judged to be at its

maximum under the existing conditions in this portion of Pescadero Creek.

Conditions in Pescadero Creek were apparently very much the same when the entire stream,

from its mouth to headwaters for a distance of 37 km, was surveyed by the CDFG during 24–30

August 1965. Young trout densities were determined by seining out several blocked-off stream

sections along 27.4 km of the creek. The average density was about 60 trout/30 m, and total

abundance was estimated at 55,385 trout. The fish were 3.6–7.6 cm long and averaged 5.3 cm,

which based on their size would suggest that all trout observed were young-of-the-year.

30

As in most California streams, fish production in Pescadero Creek was negatively impacted

by the drought of water years 1975-76 and 1976-77. During the winter of 1975-76, entry of

adults from the ocean and their migration to upstream spawning grounds were apparently

restricted due to a lack of precipitation and thus reduced stream flow. However, adult steelhead

and coho salmon did enter lower Pescadero Creek following rainfall events during mid-February

to early March 1976 (G. Scoppettone, CDFG, unpubl. memo of 25 March 1976 and 19 April

1976).

When observed by the CDFG on 10 August 1976 (R. Curtis, CDFG, unpubl. memo. of 31

August 1976), low flow conditions were exacerbated by diversions and stream flow approached

intermittency in the lower creek where no salmonids were seen. Flow was continuous but

minimal further upstream and a few juvenile trout were observed ranging in length from 5 to 15

cm. The Pescadero tributary, Honsinger Creek, was also observed during this brief survey and

found to have a minimal continuous flow that was predicted to become intermittent later in the

season. Juvenile steelhead, 10–18 cm long, reportedly inhabited a small impoundment on the

creek.

The CDFG surveyed 9.3 km of lower Pescadero Creek, from stream km 8.5 upstream from

Pescadero to Memorial Park, during the second year of the drought on 8 & 11 July 1977. The

survey report indicated that the sandbar at the mouth of the creek had only been breached twice

by storms during the winter of 1976-77. Limited entry by adult steelhead severely reduced

steelhead propagation in the system. Aside from the very low flow conditions which reduced the

quantity, the quality of physical habitat for spawning and rearing was apparently similar as in

previous surveys, except that silt deposition in the stream was perhaps enhanced because of a

lack of flushing flows. Seven dams and one logjam were identified as partial migration barriers

within the survey area, depending on actual flow conditions. Nine diversion sites were noted.

Age 0+ steelhead, averaging 3.8 cm in fork length, occurred at an estimated abundance of 35

trout/30 m in pools in a 2.1 km boulder-strewn reach, near the community of Loma Mar. Few

juvenile steelhead were seen above or below this stream reach.

On 8 August 1978, several age 0+ steelhead averaging about 6.5 cm FL were observed in a

31

23 m reach of lower Pescadero Creek (S. G. Torres and I. L. Paulsen, CDFG, unpubl. memo. of

17 August 1978). About 15 young-of-the-year steelhead, averaging about 7.5 cm FL, were also

seen immediately upstream of the fish ladder in Memorial Park. Thus, spawning of adults and

recruitment of age 0 steelhead were apparently successful following the abundant rains and high

flow conditions during the winter of 1977-78.

The 1976-77 drought greatly increased the demand on water resources in the Pescadero

Creek system, as evidenced by the volume of water applications, protests, and other related

documents contained in the CDFG files. To provide protest dismissal terms for water

applications in the lowermost 8 km of Pescadero Creek, a CDFG instream flow study determined

that a minimum bypass flow of 0.4 m3 was required during 1 November–1 May to allow passage

of upstream migrating adult steelhead and coho salmon (K. R. Anderson and I. L. Paulsen,

CDFG, unpubl. memo. of 1 October 1979). This flow would also allow for downstream passage

of post-spawning adult steelhead and emigrating smolts.

A CDFG file document from 1980 indicated that, following Fish and Game Commission

policy, catchable rainbow trout were no longer stocked into Pescadero Creek to provide for a

summer trout fishery (B. Hunter, CDFG, unpubl. letter of 6 March 1980). However, it was also

mentioned that about 10,000 yearling steelhead were planted into Pescadero annually as a stock

enhancement measure. For example, 10,120 Mad River steelhead (@ 22.0/kg) were planted on

14 April 1975; 10,070 Mad River steelhead (@ 209.4/kg) on 22 August 1978; 8,013 Mad River

steelhead (@ 23.4/kg) on 29 April 1980; and 8,140 steelhead (@ 8.2/kg) from Point Arena Ponds

(lot or egg source not specified) on 21 March 1985.

The abundance of age 0+ and 1+ steelhead was determined at the fifth and sixth road

crossings upstream from the mouth of Pescadero Creek, by use of the removal method during fall

1986 (J. J. Smith, San Jose State University, unpubl. data). Density estimates based on two–

three electrofishing passes were 32.6 and 57.1 trout/30 m at bridge 5 and 6, respectively (site

lengths were 85 m and 37 m, respectively). On 30 October 1987, trout densities were very

similar to the year before: 28.0 and 64.0 trout/30 m. The standard lengths (± SD) of trout at

each site in the 1987 survey were 71 ± 14 mm and 73 ± 17 mm; thus, most trout were age 0+ at

32

these sites.

With acquisition of the marsh lands at the mouths of Pescadero Creek and Butano Creek (see

below) by the California Department of Parks and Recreation, much attention during the 1980’s

was directed toward development of a management plan for the Pescadero Marsh Natural

Preserve. As part of this interagency effort, Smith (1987, 1990) determined the importance of

the Pescadero lagoon as rearing habitat for juvenile steelhead prior to their migration to the

ocean.

Butano Creek and tributaries

The largest tributary to the Pescadero Creek drainage is Butano Creek, which is in reality a

separate major drainage that only shares a common lagoon with Pescadero Creek. As for the

Pescadero, the contemporary record of steelhead use of Butano Creek is fairly substantial and

draws heavily from information contained in the CDFG files.

Juvenile steelhead were observed in Butano Creek during a mid-1930’s CDFG stream

survey. The surveyor had seen adult steelhead spawning and spawning success was apparently

good. Fishing pressure was noted as heavy. High quality spawning grounds existed in the

middle portion of the drainage, and small irrigation diversions were identified in the middle and

lower portions of the stream. Early CDFG stocking records showed that the population was

supplemented with 10,000 juvenile steelhead in each of 1930, 1932, 1933, and 1934; 15,000 in

each of 1935 and 1936; 20,000 (@ 1,340/kg) from Big Creek in June 1938; and 2,000 (@

2,116/kg) from Big Creek in June 1939.

The next CDFG survey occurred in December 1948. The surveyor found that a barrier

waterfall, Butano Falls, blocked upstream migration of steelhead spawners, about 4.8 km above

the entrance to Butano Canyon. Logging was underway further upstream in the watershed. One

or two adult steelhead were observed, fingerlings were abundant, and juveniles up to 15 cm were

seen in the summer. Fishing pressure on the stream was heavy during the summer trout season

when anglers fished for juvenile steelhead and resident rainbow trout, the latter of which

occurred above the barrier waterfall.

33

During a survey of Butano Creek on 25–26 August 1958, the CDFG noted that spawning

areas had become silted since the 1948 survey, the cause being the combined effect of upstream

logging operations and heavy winter rains. Rearing habitat in the form of pools and shelter was

apparently adequate for steelhead. Below Butano Falls, 5–10 cm long juvenile steelhead were

common except near the stream mouth, while above the falls young-of-the-year resident rainbow

trout were scarce, there were some 5–7.5 cm trout, and a few 15 cm trout. Few fish were seen in

the north fork of Butano Creek, and slashings from logging covered the south fork which

precluded the evaluation of fish resources there. The total survey distance, from the mouth to the

forks, was about 13 km. Fishing pressure in summer was only moderate by this time.

Problems with sedimentation and logging debris in Butano Creek were persisting when the

CDFG surveyed the stream again in July 1964. Despite the effects of poor watershed

management in the headwaters, the steelhead and rainbow trout populations also persisted

although the impacts on population growth could not be assessed based on available information.

South Butano Creek was surveyed more closely by the CDFG on 30 July 1964, from its

confluence with the main stem to the headwaters, for a distance of nearly 9 km. This stream was

regarded as an important tributary to Butano Creek because of its contribution of perennial

summer flow. The creek contained several major migration barriers and was heavily silted due

to the effects of logging. Nonetheless, a small population of resident rainbow trout was able to

exploit the small gravel patches and rearing pools. Young-of-the-year, 4–5 cm in length,

occurred in a visually estimated density of 8 fish/30 m, while older trout, 9–13 cm in length, had

a density of about 2 fish/30 m. The population was reportedly established as the result of plants

made several years before by an ex-warden of the CDFG. Fishing pressure was light.

The 1976-77 drought greatly increased the demand on water resources in the Pescadero

Creek system, as evidenced by the volume of water applications, protests, and other related

documents contained in the CDFG files. To provide protest dismissal terms for water

applications in the lowermost 7.1 km of Butano Creek, a CDFG instream flow study determined

that a minimum bypass flow of 0.3 m3 was required during 1 November–1 May to allow passage

of upstream migrating adult steelhead and coho salmon (K. R. Anderson and I. L. Paulsen,

34

CDFG, unpubl. memo. of 1 October 1979). This flow would also allow for downstream passage

of post-spawning adult steelhead and emigrating smolts.

The main tributary to Butano Creek, Little Butano Creek, is also a known steelhead/rainbow

trout stream. Early CDFG records showed that the steelhead population was supplemented with

10,000 juveniles in 1935 and 8,000 in 1936. When surveyed by the CDFG on 28 August 1958, a

6 m high silted-in flashboard dam, located about 4.5 km upstream from the confluence with

Butano Creek, marked the upstream extent of steelhead access in the Little Butano. The dam

diverted water to Upper Bean Hollow Lake via a flume. Spawning grounds below the dam were

rated as fair; the best spawning gravels for steelhead existed above the dam. Rearing habitat in

the form of pools and shelter was best in the lowermost stream area. Young-of-the-year

steelhead, 5–7.5 cm in length, were abundant in the portion of stream below the dam, and were

estimated in densities up to about 23 trout/30 m. Young-of-the-year were generally less

abundant above the dam, and were considered to be the progeny of resident rainbow trout. Near

the headwaters, resident rainbows up to about 23 cm in length were observed. Removal of the

abovementioned dam would allow steelhead access to another 2.4 km or more of production

area.

When surveyed from the mouth to headwaters by the CDFG during 10–17 August 1962,

spawning and rearing conditions in Little Butano Creek were apparently much the same as in the

1958 survey. However, a 4.5 m high bedrock falls, located about 250 m above the confluence

with Butano Creek, was identified as a complete barrier to upstream migration of anadromous

salmonids. Interestingly, this barrier was either formed during the interim, or was simply

overlooked in the 1958 survey. A culvert, located about 500 m below the flashboard dam, was

also a potential migration barrier. In addition to the abovementioned flume, there was a new

diversion at a sandbag dam. Siltation caused by old logging operations was noted as a pollution

problem. Juvenile steelhead/rainbow trout were seen from the mouth to the headwaters,

although they were scarce in the uppermost stream area. The fish above the barriers were

considered to be rainbow trout, most of which were 2.5–5 cm long young-of-the-year, but a few

10–12.5 cm trout were also seen. Trout density above the barriers was visually estimated at 15–

35

20 fish/30 m. Juvenile steelhead and coho salmon were observed below the bedrock falls.

The entire Little Butano Creek was surveyed by the CDFG on 7–8 June 1977, during the

second year of the 1976-77 drought. The status of spawning and rearing habitat for rainbow

trout was apparently much the same as in previous surveys. New potential migration barriers

and diversions were identified. Cattle caused some pollution (manure and eroded soil in the

stream) in the lower creek area. Rainbow trout, 2.5–15 cm in length, occurred at a visually

estimated density of 20 fish/30 m between the bedrock falls near the stream mouth and the

flashboard dam. Rainbow trout were not seen above this point; thus, trout distribution in the

Little Butano was greatly reduced relative to observations made during the previous 20 years.

Although the exact cause was not readily identifiable, upstream water development in Butano

State Park, which included a pumping station at a concrete dam, may have been a factor.

Evidently, this trend has not been evaluated since 1977.

Fall Creek

The Pescadero tributary, Fall Creek, was surveyed by the CDFG on 16 August 1962. An 2.4

m natural bedrock barrier limited steelhead access to the lowermost 274 m of stream. About

40% of this stream length comprised high quality spawning grounds, and old redds were

observed. Rearing habitat was apparently only suitable for age 0+ salmonids, due to the

shallowness of the creek. No diversions were seen. Steelhead and/or rainbow trout juveniles,

2.5–5 cm long, were present at a visually estimated abundance of 20 fish/30 m.

Little Boulder Creek

When surveyed by the CDFG on 15 August 1962, Little Boulder Creek was noted as an

important tributary to Pescadero Creek because of its perennial flow. Only the lowermost 1.2

km of the creek was available to steelhead because of an impassable bedrock barrier. However,

within this reach, the creek contained high quality spawning gravel and suitable rearing habitat

for steelhead. Juvenile trout, 2.5–5 cm in length, were abundant and visually estimated at 75

trout/30 m. Older trout up to 23 cm long were also observed. No fish were seen above the

bedrock barrier. There was a water diversion to a lumber mill.

36

Peters Creek

Peters Creek was surveyed by the CDFG on 5 August 1962, from its confluence with

Pescadero Creek to a natural waterfall barrier located about 9.3 km upstream. Suitable spawning

habitat for salmonids was scarce in the lowermost 2.4 km of stream due to siltation caused by

logjams, but was generally abundant further upstream. Rearing habitat in the form of pools and

shelter was apparently adequate for juvenile steelhead. Logjams consisting mostly of debris

from prior logging operations created potential barriers to fish migration in the lowermost 3.2

km of the stream. One water diversion was noted. Steelhead and/or rainbow trout were

abundant throughout the stream, at visually estimated densities of 50–150 trout/30 m. An

estimated 98% of these fish were 2.5–5 cm long (age 0+) while the remaining 2% ranged in

length from 7.5 to 20 cm.

Pilarcitos Creek Drainage During the winter of 1975-76, entry of adults from the ocean and their migration to upstream

spawning grounds were apparently restricted due to a lack of precipitation and thus reduced

stream flow. No adult steelhead were observed at one check point on Pilarcitos Creek on 26

February 1976 despite recent rainfall (G. Scoppettone, DFG, unpubl. memo. of 25 March 1976).

Arroyo Leon

The Arroyo Leon is a major tributary which has its confluence with Pilarcitos Creek at the

community of Half Moon Bay. Juvenile steelhead were present in the Arroyo Leon during a

mid-1930’s CDFG survey of the creek. Spawning grounds for steelhead were patchily

distributed, but natural propagation was successful. Two 6 m diversion dams were barriers to

steelhead migration. Fishing pressure was moderate on what was mentioned to be a small

steelhead run. The population was supplemented with 10,000 juvenile steelhead in 1930.

Pomponio Creek Drainage Within recent geological history, only the lowermost 1.6 km of Pomponio Creek has been

available to steelhead because of a 7.5 m waterfall at that point. The CDFG surveyed the entire

37

9.7 km of stream on 29 August 1958. Spawning areas were of generally poor quality above the

fall, and only somewhat better below. Pools with cover provided rearing habitat both above and

below the fall, although they were especially numerous and deep below. Local residents

supported the view that steelhead could not ascend the waterfall. Relatively many juvenile

steelhead, 5–7.5 cm long, were captured by seine and otherwise observed downstream from the

fall, along with a 56 cm post-spawner. Only two trout, 12.5 and 15 cm long, were captured at

two locations above the waterfall. These results corroborated the presence of steelhead below

the fall, and presumably resident rainbow trout above. Local residents reported trout 30–35 cm

long above the fall. There was a small reservoir near the headwaters from which water was

diverted for agricultural purposes. Releases from the reservoir reportedly maintained a perennial

flow in Pomponio Creek.

Smith (1987, 1990) captured no steelhead by seining the small Pomponio Creek lagoon on 11

& 16 June 1985 and 16 June 1986. Water quality was unsuitable for steelhead rearing in

summer. In contrast, two smolts over 20 cm long were captured there on 30 December 1985.

Smith (1990) suggested that the lagoon was used as a winter feeding area by juvenile steelhead

prior to their migration to sea.

Purisima Creek Drainage Purisima Creek has evidently not been populated by steelhead within recent geological

history because of a 10 m waterfall at the creek mouth. When surveyed by the CDFG on 18

August 1956, the creek had high quality spawning and rearing habitats for rainbow trout. Trout

were seen ranging in length from about 7.5 to 20 cm. The population had also been

supplemented with catchable rainbow trout, and the stream was managed for its resident trout

fishery. There were several flashboard dams along the middle and lower creek sections from

which water was pumped for irrigation.

The condition of the creek and status of its rainbow trout population were essentially

unchanged when surveyed by the CDFG on 26 September 1958. No catchable trout were

planted that year and it was assumed that the rainbow trout population was self-sustaining.

38

Trout plants by the CDFG were discontinued in 1963. The CDFG has conducted two

electrofishing surveys in the creek since that time, which have confirmed the persistence of the

rainbow trout population. On 25 October 1974, one 30.5 m section was sampled and 17 rainbow

trout were captured that averaged 98 ± 55 mm FL (range, 51–216 mm FL; W. E. Strohschein,

CDFG, unpubl. memo. of 13 November 1974). Forty-three trout were captured on 21 August

1986; these fish averaged 55 ± 21 mm SL (range, 35–113 mm SL; CDFG, unpubl. file data).

San Gregorio Creek Drainage The San Gregorio Creek system is one of the principal steelhead production areas in San

Mateo County. The creek apparently produced steelhead and coho salmon in commercial

quantities when surveyed in 1870 (Skinner 1962). Degradation of the system was already

underway at that time, however, due to the effects of logging, saw mills, and flour mills. So, it is

reasonable to assume that the anadromous fish populations were previously even larger than the

ones which supported the commercial fishery in 1870.

In February 1962, the local CDFG warden reportedly observed a group of about 25 adult

steelhead entering San Gregorio Creek at one time (CDFG, unpubl. field notes of 28 February

1962). The warden also indicated that maximum spawning run size in the creek was about 1,000

adults, and that the 1961-62 run was not this large but possibly comprised a few hundred fish.

Coots (1973) investigated steelhead rearing and emigration in San Gregorio Creek and

lagoon. He fished a downstream migrant trap, situated about 450 m upstream from the lagoon,

from the last week of February 1971 through 2 July 1971. Juvenile steelhead displaying smolt

characteristics ranged from 55 to 246 mm FL. Based on scale ageing and length-frequency

distributions, about 60% of smolts were one year olds, 39% were two year olds, and <1% were

three year olds or older. Movement of yearling and older (≥ 100 mm FL) smolts through the trap

followed a nearly normal distribution with tails extending from the first of March through the

end of June; the mode was at the end of April–first of May. The adipose fin was clipped from

4,775 yearling and older smolts for recovery in lagoon sampling.

Coots (1973) sampled the lagoon weekly by seining from 17 June 1971 through 26 August

39

1971. The lagoon was open to the ocean throughout most of this period, thus making it

impossible to make an accurate estimate of smolt population size using a traditional mark-

recapture model. Because only 181 clipped smolts were recovered in the lagoon, Coots (1973)

suggested that most smolts trapped and marked in the creek did not remain in the lagoon but

instead proceeded directly to the ocean. Most steelhead captured in the lagoon were

“subyearlings” and yearlings. Yearling steelhead given individual tags in the lagoon during

early July 1971 (n = 26) and recaptured there during mid- to late July 1971 (n = 5) grew in

length and weight at an average rate of 0.28 mm/d and 0.29 g/d, respectively.

Coots (1973) also captured 215 spent adult steelhead in the downstream migrant trap, of

which 123 were males and 92 were females. Although downstream movement occurred during

all four months of trapping, 83% of adults were captured during April and May 1971. Males

averaged about 43 cm FL, females about 47 cm FL, and both sexes combined about 45 cm FL

(range, 30.5–80.0 cm FL). Thus, these fish were about 22% smaller on average than those

sampled at Waddell Creek by Shapovalov and Taft (1954), assuming post-spawners were

representative of the entire sea-run spawner population. Spawning activity in the creek was

observed through the first week of May 1971. Two peaks in spawning activity were detected:

one in December 1970 and another during March–April 1971 when an increase in stream flow

allowed spawners to enter the creek. Consequently, two distinct fry emergence periods were

also observed: one in April 1971 and another that started in mid-May and continued through

June 1971.

Coots (1973) also surveyed several sections of San Gregorio Creek in August 1971 for

presence of juvenile steelhead. Few were found in a 0.5 km low-velocity reach just upstream

from the lagoon. Juveniles were abundant in a riffle area near San Gregorio, about 1.6 km

upstream from the lagoon. Young-of-the-year steelhead were abundant in riffles, and yearling

and older steelhead were present in pools and cutbank areas, in a sheltered stream area about 8

km from the mouth. Coots (1973) surmised that reduced rearing habitat associated with low

summer flow was likely a limiting factor for steelhead production in San Gregorio Creek.

The CDFG surveyed San Gregorio Creek from the mouth to its headwater streams, Alpine

40

and La Honda creeks, for a distance of about 17 km on 3 & 6 October 1975. Spawning areas

were abundant in the upper stream, and frequent but intermittent in the middle and lower stream.

Rearing habitat for juvenile steelhead was apparently adequate. No barriers to fish migration

were noted, but 19 diversions were identified, most of them for agriculture. Siltation, due to

logging and agricultural activities, was noted as a pollution problem. Juvenile steelhead were

present in the stream. Angling pressure for adult steelhead at San Gregorio Creek was noted as

moderate.

An electrofishing survey was conducted on 13 October 1975 to verify steelhead presence in

the stream (G. G. Scoppettone and K. R. Anderson, CDFG, unpubl. memo. of 3 February 1976).

In a 37 m reach about 2.3 km above the mouth, only two steelhead, 18–20 cm FL, were

captured. In 91 m approximately 6.8 km from the mouth, about 25 young-of-the-year steelhead

were shocked. In 91 m of stream near the confluence of La Honda and Alpine creeks, juvenile

steelhead were numerous and all but one (age 1+, 12.7 FL) were probably young-of-the-year.

These fish ranged from 4.8 to 11.2 cm FL, and averaged 7.4 cm FL (n = 66).

Despite a confluence with the ocean, no adult steelhead or redds were observed at three sites

on two occasions during late February–early March 1976 in San Gregorio Creek (G.

Scoppettone, CDFG, unpubl. memo. of 25 March 1976 and 19 April 1976). Entry of adults from

the ocean and their migration to upstream spawning grounds were apparently restricted due to a

lack of precipitation during the winter of 1975-76, and thus reduced stream flow. In relation to

protests of subsequent water applications, the CDFG determined that a minimum bypass flow of

0.55 m3/s in winter and spring was necessary for unimpaired upstream and downstream

migration of adult steelhead in the creek (I. L. Paulsen and K. R. Anderson, CDFG, unpubl.

memo. of 11 March 1980).

On 26 October 1979, the CDFG surveyed 4.7 km of the middle portion of San Gregorio

Creek. The stream mouth was open to the ocean at this time, following a major autumn storm.

The condition of spawning substrate and presence of fish could not be evaluated because of high

turbidity. The stream appeared to provide suitable rearing conditions for juvenile salmonids,

however, and no migration barriers were observed within the survey area. Five water diversions

41

were noted. Even though fish were not directly observed during this survey, the stream system

was still assumed to be a major production area for both steelhead and coho salmon.

An adult steelhead was observed in the upper creek area on 23 January 1981 during

inspection of an oil spill by CDFG personnel (H. W. Jong, CDFG, unpubl. memo. of 23 February

1981).

On 20 March 1985, 8,140 juvenile steelhead (@ 8.2/kg) from Point Arena Ponds in

Mendocino County were planted in San Gregorio Creek, from Skyline Boulevard downstream to

the Coyote Creek confluence.

The CDFG surveyed San Gregorio Creek during August–September 1985 in nearly its

entirety, from the headwaters at La Honda and Alpine creeks to the mouth. Spawning habitat

was rated from poor to good with an average of fair. Rearing habitat was rated as good.

Siltation persisted as a pollution problem in the stream. Two logjams created potential migration

barriers, and 33 water diversions were identified. The juvenile steelhead/rainbow trout

population ranged from moderate in size to abundant within the survey area. Two adult

steelhead, about 51–61 cm long, were observed in the upper stream.

The use of San Gregorio Creek lagoon as rearing habitat for juvenile steelhead has also been

investigated over the years. On 21 November 1969, 15 juvenile steelhead, averaging 142 mm in

length (range, 109–178 mm) were captured in the lagoon in an overnight gill net set (CDFG,

unpubl. file data). Similarly, on 4 December 1969, 49 juvenile steelhead captured in a 30 m

seine averaged (± SD) 129 ± 15 mm in length and 24.8 ± 8.1 g in wet weight (ranges, 99–163

mm and 10–46 g, respectively). The slight difference in mean size and range may have been due

to differences in gear types used on each date. Coots (1973) sampled the lagoon in 1971 (see

above). Smith (1987, 1990) determined the importance of the San Gregorio Creek lagoon as a

rearing area for juvenile steelhead prior to their migration to the ocean as smolts.

Alpine Creek

Alpine Creek is one of the main headwater tributary streams in the San Gregorio Creek

system. Juvenile steelhead were present in the creek during a mid-1930’s CDFG survey.

42

Natural propagation was noted as successful, fishing pressure as heavy, and that adult steelhead

had been caught that season. Early CDFG stocking records showed that the population was

supplemented with 8,000 juvenile steelhead in 1930; 10,000 in 1932; 20,000 (@ 917/kg) from

Big Creek in June 1938; and 5,000 (@ 2,116/kg) from Big Creek in June 1939.

A total of about 6.4 km of Alpine Creek was surveyed by the CDFG on 14 October 1963.

Spawning areas were plentiful although some gravels were cemented with sand and silt. Pools

were abundant but generally shallow, and many provided little shelter for juvenile

steelhead/rainbow trout because they were filling in with sediment. Overall, however, it was

judged that the stream provided rearing habitat for a substantial number of young steelhead.

Several pump and pipe diversions were noted on the stream. About 1.8 km above the confluence

with La Honda Creek, a 2.1 m high concrete dam formed a complete barrier to steelhead

migration. Only six juvenile steelhead/rainbow trout, 7.5–15 cm long, were seen above the

concrete dam. Below the dam, juvenile steelhead averaging 2.5–5 cm in length were highly

abundant and occurred in a visually estimated density of about 1,000 fish/30 m of stream.

The CDFG surveyed 5.3 km of Alpine Creek on 17 August 1973. Spawning and rearing

habitats for steelhead were still abundant and of high quality; the siltation problem identified 10

years earlier had apparently not progressed to any noticeable degree. The concrete dam barrier

mentioned above had been removed by use of dynamite to allow for steelhead passage. Two

large water diversions were noted. Juvenile steelhead, 5–10 cm long, occurred in densities of

about 10–20 fish/pool throughout the entire survey area, and were also present in the two

tributaries comprising the headwaters of Alpine Creek. One 18 cm long steelhead was observed

in the lower creek area. Because of its perennial flow and overall natural state, Alpine Creek

was viewed as an important component in maintaining production of the San Gregorio steelhead

stock.

On 29 March 1974, 18 adult steelhead, about 36–76 cm in length, were captured and

transported over a road culvert barrier near La Honda where they were released to continue their

spawning migration in Alpine Creek (W. E. Strohschein, CDFG, unpubl. memo. of 5 April

1974). Scales were taken from five fish which ranged from 56 to 66 cm in length. Yearling

43

steelhead, 10–12.5 cm long, were also observed during the rescue operation.

On 13 October 1975, the CDFG evaluated the success of a fishway which had been installed

to enhance steelhead passage at the aforementioned culvert barrier (G. G. Scoppettone, CDFG,

unpubl. memo. of 18 February 1976). Thirty-seven juvenile steelhead were electrofished for

length measurment from an 73 m reach of Alpine Creek, just downstream from the confluence

with Mindego Creek, a major Alpine Creek tributary. Fork lengths ranged from 4.3 to 10.9 cm,

and averaged 6.6 cm (SD = 1.8 cm); all trout captured were probably age 0+. Thus, adult

passage and parr recruitment were successful due to the fishway.

This same 73 m reach was sampled again by the CDFG on 8 August 1978 (S. G. Torres and

I. L. Paulsen, CDFG, unpubl. memo. of 17 August 1978). Despite equipment malfunction, about

25 juvenile steelhead were electrofished which ranged from 6.1 to 16.8 cm FL and averaged 8.4

cm FL. Two age-classes, 0+ and 1+, were apparently represented. Juvenile steelhead averaging

about 10 cm FL were also seen in pools near the base of the Alpine Creek fishway.

During the winter of 1975-76, entry of adults from the ocean and their migration to upstream

spawning grounds were apparently restricted due to a lack of precipitation and thus reduced

stream flow. No adult steelhead or redds were observed in Alpine Creek during late February

and early March 1976 despite recent rainfall events (G. Scoppettone, CDFG, unpubl. memo of

25 March 1976 and 19 April 1976).

On 17, 19 & 21 November 1985, the CDFG surveyed Alpine Creek from its headwaters to

the confluence with La Honda Creek, covering a distance of 6.9 km. Spawning and rearing

conditions for steelhead seemed much the same as in previous surveys. One potential migration

barrier was identified, as was one water diversion. Steelhead reportedly still spawned

throughout Alpine Creek, and a few post-spawners trapped in the stream had successfully

oversummered there in 1985.

El Corte de Madera Creek and tributaries

El Corte de Madera Creek is a major tributary to San Gregorio Creek. Juvenile steelhead

were present during a mid-1930’s CDFG survey of the stream. A barrier waterfall was noted in

44

the upper stream area, and the stream received heavy fishing pressure from local residents. Early

CDFG stocking records showed that the population was supplemented with 10,000 juvenile

steelhead in 1930; 6,000 in 1932; 10,000 in 1933; 8,000 in 1934; 10,000 (@ 847/kg) from Big

Creek in June 1938; and 3,000 (@ 1,905/kg) from Big Creek in June 1939.

When surveyed by the CDFG in July 1942, juvenile steelhead were common in the

lowermost 1.6 km of the creek, and comprised young-of-the-year, yearlings, and 2-year-olds.

Migrations barriers were present in the stream above which there were presumably resident

rainbow trout, based on the observation that young-of-the-year were present but in relatively low

densities. There were 10–15 cm long juvenile steelhead/rainbow trout throughout the survey

area. Suitable spawning grounds for steelhead were present, and no pollution sources were

noted. Four small diversions were observed, one of which required a fish ladder. The El Corte

de Madera tributary, Deer Creek, was also surveyed at this time by the CDFG. Suitable

spawning grounds for steelhead were present but scattered, and natural propagation was noted as

successful. Juvenile steelhead were observed, most of which were 5–7.5 cm in length and up to

about 15 cm.

The CDFG surveyed El Corte de Madera from the mouth to 7.2 km upstream on 4 August

1964. Gravels otherwise suitable for steelhead spawning were heavily silted. The spawning area

was estimated at about 1,472 m2, most of which was located in the lowermost 3.2 km of the

stream. Rearing habitat, in the form of pools and shelter, was adequate for juvenile steelhead,

although pools too were heavily silted. Fifteen migration barriers were identified, some of the

major ones including a 3 m high cement dam, 3.7 m and 7.6 m bedrock falls, and two 9.1 high

logging bridges. Three minor water diversions were noted. Siltation from logging operations

was a major pollution problem. Juvenile steelhead/rainbow trout averaged 5 cm in length (range,

2.5–15 cm), and ranged in visually estimated densities of about 10 trout/100 m in the upper

stream to about 550 trout/100 m in the lower stream. So, despite the apparently degraded

condition of the stream with regard to substrate quality for salmonids, production of juvenile

steelhead/rainbow trout was still substantial, at least in the lower creek area.

The CDFG made a cursory inspection of the stream on 2 April 1985 (F. Gray, CDFG,

45

unpubl. memo. of 3 April 1985) at which time two adult steelhead were observed, the larger of

which was estimated at about 3.6 kg. A heavy sediment load was noted in the stream. Cattle

grazing effects on the stream were also observed; for example, removal of streamside vegetation.

A comprehensive stream survey was conducted by the CDFG on 10, 11 & 18 October 1985,

covering 16 km from the headwaters to the mouth. Spawning sites were very limited throughout

the survey area due to siltation resulting from logging and cattle grazing. Rearing habitat was

also degraded. Several major barriers were still in place throughout the survey area, and several

new diversions had been installed since the 1964 survey. With cattle grazing, cattle wastes and

silt were polluting the lower stream, the latter caused by bank erosion. A substantial silt load

and woody debris were entering the upper stream as well, as a result of logging operations in the

drainage. Rainbow trout and/or young steelhead were observed throughout the survey area,

except in the uppermost section. Both juveniles (<15 cm long) and older trout (15–46 cm) were

observed, and their abundance was generally greater in the lower stream area.

Kingston Creek

Kingston Creek is a perennial San Gregorio Creek tributary. Nothing was present in the

CDFG file regarding the stream’s historical salmonid resources. However, on 6 June 1985, the

CDFG electrofished a 38 m long section of the stream and captured 11 juvenile

steelhead/rainbow trout which ranged from 11.7 to 16.5 cm FL and averaged 14.2 cm FL (SD =

1.8 cm; L. Bordenave, CDFG, unpubl. memo. of 15 July 1985). No young-of-the-year were

observed. This survey was made in connection with a water application on the stream.

The CDFG conducted a follow-up survey of the lowermost 0.8 km of the creek on 22 August

1985 to determine its suitability as a steelhead production area. Spawning and rearing habitats

were adequate for steelhead/rainbow trout. A possible water diversion was noted. An

impassable logjam barrier in the lower creek blocked steelhead access to most of the stream.

Therefore, it was assumed that the fish captured in June 1985 were rainbow trout.

La Honda Creek

La Honda Creek is one of the main headwater tributary streams in the San Gregorio Creek

46

system. Juvenile steelhead occurred in the creek during a mid-1930’s CDFG survey. High

quality spawning grounds were available for steelhead use, and natural propagation was

successful. One diversion dam was present, but it was equipped with a fish ladder and intake

screen. Fishing pressure for steelhead was noted as heavy. Early CDFG stocking records

showed that the population was supplemented with 12,000 juvenile steelhead in 1930; 7,000 in

1931; 12,000 in 1932; 10,000 in 1935; and 8,000 in 1936.

About 11 km of La Honda Creek, from the mouth to headwaters, were surveyed by the

CDFG on 3 August 1964. Suitable spawning gravels for steelhead were located primarily in the

lowermost 4.8 km of the stream, and comprised an area of about 22,000 m2. High quality

rearing habitat was available to salmonids. Two water diversions were noted, and there were

three complete logjam barriers and 20 partial barriers. Siltation was noted as a pollution problem

and was attributed to past logging operations. Juvenile steelhead and/or rainbow trout occurred

at a visually estimated density of 50 fish/30 m in the lowermost 4.8 km of stream. These trout

ranged from about 1.5 to 12.5 cm in length, and averaged 5 cm. No fish were seen in the upper

6.4 km of the stream.

The CDFG conducted a similar survey of La Honda Creek on 27 September 1973. Spawning

and rearing habitats were apparently in similar condition as in 1964. Several barriers and

diversions were noted, and there was an increase in pollution consisting mostly of urban debris,

in addition to the already present silt and woody debris from logging. Juvenile steelhead

occurred in the lowermost 9 km of the stream at visually estimated densities of 15–20 trout/pool

and 20–50 trout/pool in the middle and lower reaches, respectively. Most trout were 5–10 cm in

length (age 0+), although a few 15–18 cm trout (age 1+) were also seen in the lower stream.

No juvenile steelhead/rainbow trout were seen under extremely low flow conditions in La

Honda Creek above the confluence with Woodruff Creek on 10 August 1976 (M. Cogger,

CDFG, unpubl. memo. of 30 August 1976). In contrast, young-of-the-year steelhead averaging

about 6.5 cm FL were observed at this location on 4 August 1978, at a visually estimated density

of 100 fish/30 m (S. G. Torres, CDFG, unpubl. memo. of 14 August 1978).

No juvenile steelhead/rainbow trout were captured by electrofishing a 53 m reach below a

47

concrete dam in upper La Honda Creek near the community of Sky Londa on 31 May 1985 (J.

Ford, CDFG, unpubl. memo. of 19 July 1985). Lamprey ammocoetes were captured, however,

which indicated that there was an anadromous connection to this stream area, at least for the

lamprey.

The most recent comprehensive CDFG survey of La Honda Creek was made during 19–20

July 1985. Spawning areas were of low quality except for scattered sites containing high quality

gravels. Overall, though, spawning habitat was considered adequate. Rearing habitat was also

considered adequate for juvenile steelhead, although reduced stream flow and its related effects

(e.g. reduced delivery rate of drifting food particles) was judged to be a limiting factor for

steelhead production. Many migration barriers (mostly logjams) and five water diversions were

noted, and a campground construction site was identified as a pollution source. Juvenile

steelhead and/or rainbow trout, up to 20 cm in length, were observed throughout the survey area,

except in the uppermost sections near Sky Londa where the stream was dry.

The most recent observation of juvenile steelhead in La Honda Creek was made on 2 October

1987 when a kill of 60 juvenile steelhead (estimated at a density of 1,243 trout/km) resulted from

a massive sediment load to the stream which greatly altered water quality and filled in pool

habitat (L. Ulmer, CDFG, unpubl. file letter of 13 October 1987).

San Pedro Creek Drainage San Pedro Creek is somewhat unique in that it is a highly urbanized stream which continues

to support a naturally reproducing steelhead stock, in part due to the interests and efforts of local

residents in the community of Pacifica. From an historical perspective, the CDFG files indicate

that adult steelhead were seen ascending the stream to spawn in April 1941. At that time,

ranches dominated the drainage area and it is assumed that the creek system was in relatively

good condition. There was tidewater at the stream mouth, but no real lagoon. The main stem

was about 4 km long and formed by flow from three forks, the “east” fork being the only one

with perennial flow. Water was diverted from the creek system for irrigation.

However, by 1971 the creek habitat was severely degraded due to the effects of garbage

48

dumping, rat poisoning, and wastewater discharge in conjunction with urbanization of the area.

Apparently, a fish kill had occurred on 22 December 1970. Local citizens formed a committee

to promote the protection and enhancement of San Pedro Creek (J. Ladd, CDFG, unpubl. memo.

of 14 January 1971).

Two adult steelhead were seen in the stream during a single spot check on 6 April 1972 (E.

Armstrong, CDFG, unpubl. memo. of 7 April 1972). Adults ascended the stream during the

winter of 1972-73 as well (D. C. Erman, UC Berkeley, unpubl. letter of 9 February 1973). San

Pedro Creek was surveyed by the CDFG in July 1973. Urban debris was still common in the

streambed, and spawning areas were both quantitatively and qualitatively limited. Rearing

habitat was adequate, with the presence of pools and abundant riparian cover. Several barriers to

upstream migration were identified, especially at culverts, and several diversions were observed,

the largest being that for the North Coast County Water District. Storm drains discharged into

the creek. Juvenile steelhead were observed in all reaches of the main stem. As determined

from electrofishing samples, the trout ranged from 3.8 to 20.3 cm in length and averaged 8.9 cm.

Steelhead were observed above all culverts on the main stem, but only below the water district

diversion in the south fork of the creek system.

The size-structure of the juvenile steelhead population in San Pedro Creek was investigated

on four occasions during the 1970’s. On 3 July 1973, steelhead were sampled by electrofishing

at four main stem stations (K. R. Anderson, CDFG, unpubl. memo. of 29 August 1973). The fish

ranged in size from 3.6 to 16.0 cm FL, and averaged 8.0 cm FL (SD = 1.8 cm, n = 220). Thus,

rearing juveniles were age 0+ and 1+, and 0+ trout were proportionately dominant in number.

Abundance estimates were also made in late summer 1973, by electrofishing seven stream

reaches (15–61 m) and applying the two-pass removal method of population estimation (K. R.

Anderson, CDFG, unpubl. memo. of 13 November 1973). Juvenile steelhead densities ranged

from about 2.0 to 7.6 trout/m, and averaged (± SD) 5.1 ± 2.3 trout/m. Despite its somewhat

degraded condition, the creek system continued to support relatively high densities of juvenile

steelhead.

On 10 October 1974, the average size of juvenile steelhead electrofished in four main stem

49

reaches was 10.2 cm FL (range, 5.1–18.8 cm FL; n = 125). The largest trout (21.3 cm FL) was

found in the South Fork San Pedro Creek (K. R. Anderson, CDFG, unpubl. memo. of 28 October

1974). On 17 September 1976, the average size of juvenile steelhead electrofished in two main

stem reaches was 8.9 cm FL (range, 3.3–17.3 cm FL; n = 26). Overall abundance of juvenile

steelhead was apparently lower than in previous surveys (K. R. Anderson et al., CDFG. unpubl.

memo. of 24 September 1976). Finally, on 15 November 1979, the mean size of juvenile

steelhead electrofished in two main stem reaches was 9.4 cm FL (range, 5.6–16.8 cm FL; n = 43)

(I. L. Paulsen and L. Fish, CDFG, unpubl. memo. of 21 November 1979). Estimated densities

were 0.2 and 0.9 juvenile steelhead/m, which were much lower than those measured in 1973.

Despite apparent differences in relative year-class strength, these four surveys demonstrated

that the juvenile steelhead population in San Pedro Creek consistently comprised two age-

classes, 0+ and 1+, and that the 0+ group dominated numerically. The relatively small

proportion of 1+ trout present in any given survey indicates that the main smolting age of

steelhead in San Pedro Creek is age 1.

During the winter of 1975-76, entry of adults from the ocean and their migration to upstream

spawning grounds were apparently restricted due to a lack of precipitation and thus reduced

stream flow. Consequently, no adult steelhead or redds were observed in San Pedro Creek on 26

February 1976. Several adult steelhead, two estimated at 2.7 kg each, were observed in the creek

on 1–2 March 1976, however. The local warden estimated that 60 adult steelhead had been

poached at Adobe Road Bridge during this period (G. Scoppettone, CDFG, unpubl. memo of 25

March 1976 and 19 April 1976).

In March 1978, about 600 steelhead died in San Pedro Creek due to the storm drain

discharge of an unknown poison, possibly chlorinated swimming pool water (The Times, San

Mateo, 22 June 1978).

By 1985, the headwaters of San Pedro Creek were protected by virtue of their inclusion in

San Pedro Valley County Park. In March 1985, 800 Dry Creek steelhead (8.8/kg) were stocked

into the stream. When surveyed by the CDFG in May 1985 (J. Ford and L. Bordenave, DFG,

unpubl. memo. of 29 July 1985), the creek system was in good condition overall. Steelhead

50

spawning habitat was abundant in the upper main stem, or middle fork, but lacking in the north

and south forks. Most spawning occurred within the park boundaries. Spawning reportedly

occurred as late as May, and during the 1984–1985 spawning season, there were about 40 pairs

of spawning steelhead within a 30 m spawning reach. Obstructions for upstream migrating

spawners were identified, and storm drain pollution was still cited as a problem. Indeed, on 10

March 1987, 600–700 steelhead fry, yearlings, smolts, and adults were killed in the north fork

and 2 km of the main stem as the result of a toxic storm drain discharge, probably chlorinated

swimming pool water.

The lowermost 880 m of San Pedro Creek was surveyed by the CDFG on 28 September 1988

(C. Dayes and D. Becker, CDFG, unpubl. memo. of 21 October 1988). Age 0+ and 1+

steelhead, up to about 20 cm in length, were observed throughout the reach, including the

lagoon. Riffles provided over 464 m2 of spawning gravel for steelhead. Rearing habitat was

good to excellent, and included abundant streamside riparian vegetation. Notably, the creek had

continuous flow to the lagoon and contained two consecutive year-classes of juvenile steelhead,

despite two consecutive drought years.

Tunitas Creek Drainage The CDFG surveyed the upper 6.4 km of Tunitas Creek on 18 April 1962, and the lower 3.2

km on 11 May 1962. Spawning areas for steelhead were scarce in the headwaters, but of high

quality in the lower 3.2 km. Pool development and shelter were rated as fair, although the

frequency of pools was low, thus potentially limiting rearing habitat. Logjams occurred

throughout the stream. One logjam about 1.2 km above the mouth was a probabe partial

migration barrier to adult steelhead. Several small pump diversions for domestic use were

observed. Steelhead usually had access to the lowermost 3.2 km of stream, up to the confluence

with the East (South) Fork, and no juvenile steelhead were observed above this point. The

average of four visual estimates of abundance was 26 trout/100 m. Very few steelhead over 13

cm were observed. The local CDFG warden estimated the annual steelhead run at 100–200

adults.

51

In contrast to the 1962 survey, juvenile steelhead were found in Tunitas Creek above the

confluence with the East Fork when sampled by the CDFG on 25 October 1974 (W. E.

Strohschein, CDFG, unpubl. memo. of 13 November 1974). Fourteen steelhead, 56–137 mm

FL, were captured in a single electrofishing pass through 7.5 m of stream.

During the winter of 1975-1976, entry of adults from the ocean and their migration to

upstream spawning grounds were apparently restricted due to a lack of precipitation and thus

reduced stream flow. No adult steelhead were observed in lower Tunitas Creek on 25 February

1976 even though there was a shallow confluence with the ocean (G. Scoppettone, CDFG,

unpubl. memo of 25 March 1976).

East Fork Tunitas Creek

The CDFG surveyed the entire 1.6 km of the East Fork Tunitas Creek on 28 July 1964. This

stream was described as a valuable steelhead spawning and young-of-the-year rearing area.

High quality spawning gravels were continuous throughout the stream. Small pools and cover

provided excellent rearing conditions. There were nine windfall barriers although there were

fish above all of them. Only young-of-the-year steelhead, averaging about 4 cm, were observed,

at a visually-estimated density of 164 trout/100 m throughout most of the creek.

Whitehouse Creek Drainage Although no detailed historical information was discovered for Whitehouse Creek,

Shapovalov and Taft (1954, p. 201) mentioned that the stream supported a very small steelhead

run, relative to the runs observed at Scott and Waddell creeks during the 1930’s–40’s. In 1929,

the steelhead population had been supplemented with 4,000 juveniles from the Scott Creek Egg

Taking Station. A more recent CDFG document (P. Bontadelli, CDFG, unpubl. memo. of 16

November 1987) stated that “Whitehouse Creek has historically been and continues to be a

steelhead stream”. The CDFG surveyed the creek from its headwaters to mouth (8.2 km) on 22

June 1978. The uppermost 1 km was dry. Most of the creek had adequate spawning areas for

steelhead, with quality generally increasing with distance upstream. Rearing habitat, in the form

of pools and cover, was also adequate. There were, however, heavy silt and detritus deposits in

52

the lowermost 5 km of stream due to adjacent agriculture and grazing. In addition, the

lowermost 1 km of stream contained several migration barriers: the concrete culvert passing the

stream under Highway 1, a 2 m-high man-made log dam near Highway 1, and debris jams

caused by streamside vegetation cleared for agriculture and bulldozed into the creek. The only

surface diversion observed also occurred in this reach. There was also a light silt load in the

upper creek from the adjacent dirt road. Juvenile steelhead/rainbow trout, visually-estimated at

about 3 cm long, were only observed in one reach about 4–5 km above the mouth.

When surveyed again by the CDFG on 2 May 1988 and 1 June 1988, suitable spawning and

rearing habitats for steelhead were still found throughout most of the stream. Siltation from

cattle grazing and other streamside activities continued to degrade habitat quality, especially in

the middle and lower stream areas. In addition to the migration barriers identified in 1978, many

more were seen through most of the stream. Notable were a sacked concrete dam directly below

the Highway 1 bridge, a 4.6 m long culvert 1.2 m above water surface elevation, and various

other logjams, dams, road crossings, and blocked culverts. One active surface diversion was

seen, which carried water to Chandler Reservoir, an off-stream storage facility. Despite the

various impediments to access, juvenile steelhead occurred at several locations throughout the

lower half of the drainage up to a concrete dam that was a complete barrier. Three live adult

steelhead and one carcass were also seen. Age 0+ resident rainbow trout were observed above

the concrete dam. Overall, Whitehouse Creek was rated as good to excellent for steelhead

production, aside from localized siltation. The main factors limiting the population appeared to

be migration barriers and low summer stream flow.

SANTA CRUZ COUNTY

Aptos Creek Drainage Snyder (1913) found juvenile steelhead/rainbow trout in Aptos Creek when he sampled

there in summer 1909. Juvenile steelhead were present in Aptos Creek during a 1934 CDFG

survey. Spawning grounds were found throughout the stream, natural propagation was rated as

very good, and fishing pressure for steelhead was heavy. When surveyed again by the CDFG in

53

May 1941, the condition of the stream was apparently similar as in 1934, although both young-

of-the-year and older steelhead occurred in low abundance in the stream, and none was seen in

the lagoon.

Aptos Creek was not surveyed again by the CDFG until July 1960. At that time, high

quality spawning and rearing habitats were still available, and no migration barriers or diversions

were seen. Densities of juvenile steelhead in non-pool habitats ranged from about 5–10 trout/30

m in the upper survey area to 40–65 trout/30 m in the lower stream. In pools, densities ranged

from about 10–20 trout/pool. Siltation below Bridge Creek was believed to have reduced the

steelhead production capacity of the stream somewhat through loss of cover for rearing fish.

Fishing pressure was noted as light.

In a summer 1965 CDFG survey, it was estimated that nearly 9 km of the stream

contained intermittent reaches of spawning gravels, 13 km contained high quality rearing habitat,

and there were no barriers or diversions. The average density of juvenile steelhead over the

entire stream was about 3.3 trout/m, except for a 0.8 km reach which contained 4.6 trout/m.

(Fish were sampled by use of a Braille seine, cresol poisoning, and direct visual counts). The

estimated total abundance of young steelhead was over 43,000 trout. These fish ranged in length

from 4.3 to 8.9 cm, and averaged 6.1 cm. Thus, all steelhead observed were young-of-the-year;

natural propagation was rated as good. Fishing pressure was noted as moderate.

The adult steelhead run in Aptos Creek as of 1968 was estimated by the CDFG at about

1,500 fish, although the method used to attain this estimate was not described.

In April 1976, the CDFG supplemented the Aptos Creek steelhead population with 1,000

juveniles from the Noyo River.

In late fall 1981, the mean ± SD density of smolt-sized steelhead at five sites was 3.1 ±

2.9 trout/m, which was somewhat below the county-wide average (derived from Smith 1982b).

The mean ± SD of the site-specific mean lengths of these fish was 94 ± 11 mm SL, which was

near average.

The creek was surveyed by the CDFG in late May 1982, from the mouth to 2.4 km above

the confluence with Bridge Creek, following the disastrous rainstorms of January 1982 (L.

Turner, CDFG, unpubl. memo. of 1 June 1982). Siltation, as a result of landslides, had degraded

54

both spawning and rearing habitat. In addition to landslides, logjams created full or partial

barriers to fish migration. Fish food organisms were scarce, and no juvenile steelhead were

observed. Apparently, the pre-smolts present the previous fall were killed or displaced by the

high flow, or emigrated to the ocean. In addition, the entire 1982 year-class was apparently

eliminated by siltation of the gravels where eggs were incubating.

The most recent CDFG surveys of Aptos Creek were conducted during 12–26 August

1985 (D. Marston, CDFG, unpubl. memo. of 12, 20, & 26 August 1985). The stream was

surveyed over nearly 9 km, from the mouth to the area known as the bottom of the incline,

within the Nisene Marks State Park boundary. Within the lowermost 2.4 km, there remained a

logjam from the 1982 flood which created at least a partial barrier to upstream migration of adult

steelhead. Suitable spawning areas were lacking below the barrier, but as one progressed

upstream through the survey area, substrate particle size increased on average and the overall

abundance of suitable spawning gravel increased. Pools and shelter for rearing juveniles were

present throughout the survey area. Yearling steelhead were abundant below the barrier in the

lower stream, but few young-of-the-year were present there. Trout were also present above the

barrier, and their abundance generally increased toward the upstream area. Their lengths ranged

from about 2.5 to 20 cm. Some of these fish were believed to be resident rainbow trout. In the

uppermost 2.8 km of the survey area, both young-of-the-year and yearling steelhead/rainbow

trout were abundant. A state park ranger had seen an adult steelhead in this area.

Bridge Creek

The Aptos Creek tributary, Bridge Creek, was surveyed by the CDFG in July 1960.

Spawning areas were fair to good in the middle and lower stream, but very poor above an

impassable waterfall barrier, about 2.5 km upstream from the confluence with Aptos Creek.

Rearing habitat was adequate, especially in the middle and lower stream. Juvenile steelhead, 5–

15 cm long, were common throughout the middle and lower stream, but absent above the

waterfall.

Bridge Creek was not surveyed again until May 1982, following the devastating storms

of January 1982 (L. Turner, CDFG, unpubl. memo. of 2 June 1982). Landslides, logjams, and

55

falls rendered the stream unuseable for steelhead. Besides restricted access due to barriers, the

stream bottom was composed primarily of rubble and silt. No fish were observed in the creek at

that time, although juvenile steelhead/rainbow trout were reportedly present in Bridge Creek in

1985 up to Maple Falls (D. Marston, CDFG, unpubl. memo. of 26 August 1985).

Valencia Creek

In late fall 1981, the mean ± SD density of smolt-sized steelhead at two sites in the

Aptos Creek tributary, Valencia Creek, was 4.9 ± 0.9 trout/m, which was above the county-wide

average (derived from Smith 1982b). The mean ± SD of the site-specific mean lengths of these

fish was 94 ± 0 mm SL, which was near average.

Arana Gulch Drainage Arana Gulch is a small urbanized stream which discharges into Woods Lagoon, the

location of the Santa Cruz Small Craft Harbor. Mention of steelhead in this stream dates back to

1966 in the CDFG files; the run was apparently small. A 46 m section of Arana Gulch was

surveyed by the CDFG in January 1983 (J. Lorenzana, CDFG, unpubl. memo. of 26 January

1983). Two 1-year-old juvenile steelhead (8.5 and 11 cm in length) were captured, about 1.6 km

above the harbor. Generally, the stream was in poor condition due to upstream erosion and

resultant sedimentation. Suitable spawning substrate for steelhead was lacking in the survey

reach, and rearing habitat was very limited. An adult female steelhead was reportedly observed

spawning in Arana Gulch on 1 March 1984 (F. Gray, CDFG, unpubl. memo. of 7 March 1984).

The size of the fish was estimated at 3.5 kg.

Baldwin Creek Drainage As a relative measure of adult run size, Shapovalov and Taft (1954, p. 201) mentioned

that the Baldwin Creek steelhead run was smaller than those observed at Scott and Waddell

creeks during the 1930’s–40’s. When surveyed in its entirety by the CDFG on 16 May 1960,

Baldwin Creek was described as having a perennial flow that was not diverted during the

summer, and a larger population of O. mykiss than either of nearby Majors and Laguna creeks to

56

the north. Salmonid spawning areas were proportionately abundant, and juvenile rearing habitat

in the form of pools and cover was seemingly ample and of high quality. A concrete apron was

identified as a migration barrier for steelhead, and three flashboard dams as potential barriers,

one of which created a sizeable reservoir about 1.6 km above the mouth of the stream. Juvenile

trout were seen in nearly every pool along the 4.8 km survey area; their lengths ranged from

about 2.5 to 15 cm. The landowner at Baldwin Creek estimated the average adult run size to be

50 steelhead.

In late fall 1981, the mean ± SD density of smolt-sized steelhead at five sites was 3.6 ±

3.4 trout/m, which was very near the county-wide average (derived from Smith 1982b). The

mean ± SD of the site-specific mean lengths of these fish was 94 ± 7 mm SL, which was also

near average.

Finny Creek Drainage Although no detailed historical information was discovered for Finny Creek, Shapovalov

and Taft (1954, p. 201) mentioned that the stream supported a very small steelhead run, relative

to the runs observed at Scott and Waddell creeks during the 1930’s–40’s.

Laguna Creek Drainage As a relative measure of adult run size, Shapovalov and Taft (1954, p. 201) mentioned

that the Laguna Creek steelhead run was smaller than those observed at Scott and Waddell

creeks during the 1930’s–40’s. The lowermost 6.4 km of Laguna Creek were surveyed by the

CDFG on 26 February and 1 March 1960. Suitable spawning areas for salmonids were lacking

and thought to be a limiting factor to steelhead production. In contrast, rearing habitat for

juvenile steelhead, in the form of pools and cover, was abundant and of high quality. Natural

bedrock falls, beginning at about 3.2 km above the mouth, were identified as migration barriers

to adult steelhead. Water was diverted from the stream for both domestic and agricultural uses.

An adult steelhead, about 61 cm in length, was seen below the first bedrock barrier. Resident

rainbow trout were noted in pools in upstream sections of the creek.

In late fall 1981, the mean ± SD density of smolt-sized steelhead at five sites was 2.3 ±

1.5 trout/m, and thus below average (derived from Smith 1982b). The mean ± SD of the site-

57

specific mean lengths of these fish was 102 ± 18 mm SL, which was above the county-wide

average.

In June 1985, the CDFG surveyed two reaches, totalling about 460 m, in lower Laguna

Creek downstream from the bedrock falls (D. Marston, CDFG, unpubl. memo. of 28 June 1985).

Spawning habitat was limited in one reach but abundant in the other. Rearing habitat for

juvenile steelhead was adequate. Pollution types were silt and cattle waste. Both young-of-the-

year and yearling steelhead were observed. There was no indication of overall stream condition

and status of the steelhead/rainbow trout population.

Liddell Creek Drainage As a relative measure of adult run size, Shapovalov and Taft (1954, p. 201) mentioned

that the Liddell Creek steelhead run was smaller than those observed at Scott and Waddell creeks

during the 1930’s–40’s. In late fall 1981, the density of smolt-sized steelhead at one site below

the confluence of the east and west headwater forks of Liddell Creek was 2.0 trout/m, which was

below average (derived from Smith 1982b). The mean length of these fish, 112 mm SL, was

well above average. The mean ± SD density of smolt-sized steelhead at two sites in the west

fork was 1.6 ± 2.3 trout/m, and thus below the county-wide average (derived from Smith

1982b). The mean length of these fish, 104 mm SL, was above average. The mean ± SD density

of smolt-sized steelhead at five sites in the east fork, 1.0 ± 0.5 trout/m, was below average

(derived from Smith 1982b). The mean ± SD of the site-specific mean lengths of these fish, 87 ±

12 mm SL, was also below average.

Majors (Coja) Creek Drainage Although no detailed historical information was discovered for Majors Creek,

Shapovalov and Taft (1954, p. 201) mentioned that the stream supported a steelhead run which

was smaller than those observed at Scott and Waddell creeks during the 1930’s–40’s. According

to early CDFG records, the Majors Creek steelhead population was supplemented with a plant of

2,500 juveniles (@ 1,023/kg) from Brookdale Hatchery on 25 July 1938. During 1940–44,

juvenile resident rainbow trout were planted at sizes of 176–1,235/kg and total annual weight

allottments of 1.6–16.3 kg. The April 1945 allottment was 5,000 juvenile rainbow trout at 7.5/kg

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(total allottment, 7.1 kg).

As of 1953, most, if not all, of the flow of Majors Creek was diverted for use by the City

of Santa Cruz, and steelhead fishing in 4.8 km of available tidewater was poor (CDFG, unpubl.

field notes of 24 June 1953).

The lowermost 4.8 km of the creek were surveyed by the CDFG on 6 May 1960. A 4.6

m waterfall about 0.8 km upstream from the mouth marked the limit for upstream migration of

steelhead. Another major migration barrier was the 4.6 m City of Santa Cruz dam about 3.2 km

from the mouth. Spawning gravels available to steelhead in the lowermost 0.8 km of the stream

were apparently scarce, but were more abundant for resident rainbow trout between and above

the barriers. Rearing habitat in the form of pools and cover was also poor for steelhead and

generally better for resident rainbow trout in upstream sections. Siltation, due to extensive

logging damage in the watershed, was a pollution problem in the lower stream below the Santa

Cruz dam. About 200 young-of-the-year steelhead, 2.5 cm in length, were counted in the 0.8 km

of stream below the waterfall barrier. Only six rainbow trout, 10–25 cm long, were seen

between the migration barriers. Densities of 10–15 cm long trout above the dam were about 125

fish/km and 60 fish/km in two consecutive 0.8 km reaches. Silt, in addition to low summer flows

because of the diversion, were thought to limit trout production below the dam.

In late fall 1981, the mean ± SD density of smolt-sized steelhead at six sites was 2.6 ±

2.4 trout/m, which was below the county-wide average (derived from Smith 1982b). The mean ±

SD of the site-specific mean lengths of these fish was 89 ± 9 mm SL, which was below average.

On 27 October 1983, the CDFG made a single electrofishing pass through a 46 m section

below the Santa Cruz dam and above the lower waterfall barrier and captured 33 rainbow trout

which averaged XX mm FL (range, XX–XX mm FL; in prep). Due to dam operations and other

factors, sediment input into this portion of the stream was high. Low flow conditions below the

dam possibly increased predation risk of the trout (F. Gray, CDFG, unpubl. memo. of 8

November 1983).

The CDFG surveyed Majors Creek on 21 November 1988, from the mouth to its

headwater east and west branches. Spawning habitat was limited throughout the survey area due

to the persistently high sediment load. However, there were scattered sections of exposed, loose

59

gravels in high gradient areas where the flushing effect of the flow was presumably greatest.

Rearing habitat in the form of pools and cover was apparently quite adequate for salmonids.

Waterfalls, dams, culverts, and logjams created either potential or complete migration barriers

for steelhead. Three diversions were noted. The distribution of O. mykiss within the drainage

was the same as in earlier surveys: juvenile steelhead inhabited the lowermost 0.8 km of the

stream below the first waterfall barrier, while resident rainbow trout occurred in both the main

stem and branches above the waterfall barrier. The average total length of resident rainbow trout

in the upper main stem and west branch was XX mm (range, XX–XXX mm TL; in prep). Local

residents indicated that the adult steelhead run in Majors Creek was large at one time, and that it

had supported a local consumptive fishery.

Medler Creek Drainage Although no detailed historical information was discovered for Medler Creek,

Shapovalov and Taft (1954, p. 201) mentioned that the stream supported a steelhead run which

was smaller than those observed at Scott and Waddell creeks during the 1930’s–40’s.

Pajaro River Drainage, including portions in Monterey, San Benito, and Santa Clara counties

Relatively detailed information on the historical distribution of juvenile

steelhead/rainbow trout in the Pajaro River drainage was available because of the comprehensive

surveys conducted by Snyder (1913) in 1909, the CDFG in 1967 (Lollock 1968), Smith (1982a)

during 1972–74, and Smith (1982b) in 1981. The CDFG files also contained a variety of

information from over the years which is included in the following accounts.

Snyder (1913) collected juvenile steelhead at four mainstem Pajaro River sites: upstream

from the Corralitos Creek confluence to shortly above the San Benito River confluence. The

species was neither present in the main stem below the Corralitos Creek confluence nor above

the Uvas Creek confluence. Juvenile steelhead/rainbow trout were also present in the main stem,

from its upper to lower reaches, during a 1934 CDFG survey. Spawning grounds apparently

existed all along the river. Rainbow trout were not planted because of a high density of exotic

predatory fishes present in the stream and lagoon, such as black bass (Micropterus spp.) and

60

striped bass (Morone saxatilis), respectively.

By 1960, juvenile steelhead use of the lower Pajaro River as rearing habitat may have

ceased, as none was captured at the Highway 101 crossing or in the lagoon when sampled with a

seine and gill net by the CDFG during 9–10 December 1959 (M. R. Schreiber, CDFG, unpubl.

intraoffice corr. of 24 February 1960). Fish collections made in the lower Pajaro with a minnow

seine during 1964–66, from near the mouth to near the Highway 101 crossing, also revealed an

absence of juvenile steelhead (R. N. Lea, unpubl. fish collection data of 20 September 1964–5

June 1966).

Adult steelhead were reportedly taken by anglers in the Pajaro River lagoon in late

January 1962, but intermittent flow in the lower river prevented the ascent of the spawning run

(R. N. Hinton, CDFG, unpubl. field notes of 28 January–12 February 1962). By 5 February

1962, steelhead were taken as far upstream as the Highway 1 crossing, and they were migrating

into tributaries such as Eureka Gulch on Corralitos Creek and possibly lower Uvas Creek by 12

February 1962.

The 1963-64 steelhead run was reportedly the largest and comprised the largest fish since

1955 (M. L. Johnson, CDFG, unpubl. memo. of 18 March 1964). The local game warden

estimated the Pajaro steelhead run at 1,500 adults, and spawning occurred in Corralitos Creek

and its tributary, Brown’s Valley Creek, in Pescadero Creek as far upstream as about 5 km, in

Uvas Creek, and at a gravel plant near Gilroy in the main stem (see below for further information

on the tributaries mentioned). As of 1965, the average annual steelhead spawning run was

estimated at about 1,000 adults (M. L. Johnson, CDFG, unpubl. memo. of 1 April 1965). Run

size was generally greater in years of high rainfall. As part of a planning effort, the CDFG listed

the annual steelhead spawning run in the Pajaro River at about 2,200 fish (California Department

of Fish and Game 1965). Lollock (1968) reported that the annual run fluctuated between about

500 and 2,000 adult pairs, based on local game warden observations during the previous decade

or so (M. L. Johnson, CDFG, unpubl. memo. of 22 August 1966). The 1965-66 run was

conservatively estimated at 1,000 spawning pairs.

When the Pajaro drainage was surveyed by the CDFG during July–August 1967 (Lollock

1968), the Pajaro River lagoon was used primarily as a migration corridor for adult steelhead

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returning to spawn in the river system, and for steelhead smolts emigrating to the ocean. The

sandbar at the mouth was seldom completely closed, and so passage to and from the ocean was

possible during most of the year. The lagoon was apparently not an important rearing area for

juvenile steelhead, based on a complete lack of steelhead captures during this and previous

surveys (see above). Agricultural drains were a persistent source of plant nutrients and probably

pesticides. The Watsonville sewage treatment plant and storm drain system were occasional

pollution sources, and in 1967 a large sediment load entered the lower river from the Granite

Rock Company which silted fish habitat in the upper lagoon.

About 40 km of the main stem Pajaro River was also surveyed at this time, from the

upper end of the lagoon to San Felipe Lake in the Santa Clara-San Benito counties portion of the

river (Lollock 1968). The lower river below the Granite Rock Company’s quarry was heavily

silted and no longer served as spawning and rearing habitat for steelhead, but remained

important as a migration corridor to upstream areas. The lower river area was also channelized

annually for flood control purposes. The river section from the quarry to the Highway 101

crossing contained high quality spawning and rearing habitat, although no juvenile steelhead

were observed during this survey. Water was extracted from the river by several pumps along

this section, for agricultural and industrial uses. The section upstream from Highway 101 was

again unsuitable for steelhead spawning and rearing, but important for migration to and from

Uvas and Llagas creeks. Types and sources of pollution included sediment from the Granite

Rock Company, which eliminated steelhead spawning and rearing habitat in the lower Pajaro

River, and pesticides from agricultural drainage. The Granite Rock Company compensated the

CDFG for the stocking of 5,000 Mad River steelhead yearlings, as mitigation for losses due to

their sediment input in the lower river (M. L. Johnson, CDFG, unpubl. memo. of 17 December

1974).

Conditions in the lower Pajaro River remained unimproved for steelhead spawning and

juvenile rearing when, on 24 July 1973, an electrofishing survey in three sections downstream

from Murphy’s Crossing revealed the continued absence of steelhead (R. Johansen, CDFG,

unpubl. memo. of 13 August 1973). This finding was corroborated by fish collections made in

the lagoon and lower river during 1970–1974 by local ichthyology students (G. M. Cailliet,

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Moss Landing Marine Laboratories, unpubl. file letter and attachments of 30 May 1974).

Smith (1982a) did not find juvenile steelhead at the four mainstem Pajaro River sites,

upstream from the Corralitos Creek confluence to shortly above the San Benito River

confluence, where they were collected by Snyder (1913). The degradation of steelhead

spawning and rearing habitat, as described above, was cited as the likely cause for this reduction

in distribution. These conditions persisted when Smith (1982b) electrofished five mainstem

reaches in late fall 1981, from the river mouth to the mouth of Pescadero Creek, and captured no

steelhead, although several other native fish species were present. Smith (1982a) found that

spawning success was low throughout the system during the very dry water years of 1971-72,

1975-76, and 1976-77. Steelhead spawning occurred at two mainstem sampling sites in the wet

water year of 1972-73, but very few young survived summer rearing conditions.

On 6 March 1985, the CDFG planted 6,750 juvenile steelhead (@ 9.9 fish/kg) of Warm

Springs Hatchery (Russian River, Sonoma County) origin into the Pajaro River at the Highway

101 crossing.

The current status of the Pajaro River steelhead population is uncertain (K. R. Anderson,

CDFG, pers. comm. of 9 July 1992). Nehlsen et al. (1991) listed the Pajaro River steelhead

stock as being at a high risk of extinction.

Corralitos Creek and Tributaries

The Pajaro River tributary, Corralitos Creek, is the first major tributary that spawning

steelhead can access as they migrate into the Pajaro River drainage. Neither this creek nor its

tributaries were sampled by Snyder (1913), but CDFG records beginning in the 1930’s, and

Smith’s (1982a,b) later work, provide a comprehensive impression of steelhead and rainbow

trout use in these streams.

The CDFG surveyed an approximate 0.4 km portion of upper Corralitos Creek, and

about 1.6 km of the Corralitos tributary, Shingle Mill Gulch, to Grizzly Flat, on 16 November

1960. There were scattered spawning areas in Corralitos Creek downstream from Shingle Mill

Gulch, but virtually none in the tributary itself. Rearing habitat was adequate for young

steelhead throughout the area. There were several small domestic diversions. Juvenile steelhead

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and/or rainbow trout were present throughout the survey area. Density estimates were made by

the CDFG along Corralitos Creek on 1 July 1960. There was an average of 30 trout/30 m in the

lower reaches; 20 trout/30 m between Eureka Gulch and Grizzly Flat in Shingle Mill Gulch; and

10 trout/30 m in upper Corralitos Creek. As of 1960, Corralitos Creek was allotted monthly

plants of 2,000 catchable rainbow trout during May–July of each year. Angling pressure was

high for rainbow trout during late spring–early summer, and in addition to planted trout, the

catch probably also included juvenile steelhead.

Lower Corralitos Creek, from the mouth to Eureka Gulch, was surveyed by the CDFG on

20 January 1961. Gravel occurred in scattered patches throughout the survey area, but the

substrate contained a high proportion of sand which may have reduced the quality of these areas

for steelhead spawning. Suitable juvenile steelhead rearing habitat, in the form of pools and

cover, was found especially upstream from the town of Corralitos. The City of Watsonville

maintained a diversion dam on the creek, equipped with an adequate fish ladder, about 1.1 km

north of Corralitos. This diversion removed a large proportion of the stream flow. Several other

pump diversions and wells were also observed along the stream. Urban debris polluted the lower

reaches of the creek. Few juvenile steelhead and/or rainbow trout were seen; steelhead

production below the diversion dam was apparently limited by a lack of stream flow and suitable

spawning substrate. Fishing pressure was high above Corralitos during late spring–early

summer when catchable rainbow trout were planted (see above).

An adult steelhead was observed at the base of the fish ladder at the Watsonville

diversion dam on 14 February 1962. Brown trout, which were introduced to Corralitos Creek

during the 1940’s, were captured throughout the creek by anglers during spring 1962; one fish

was reportedly about 38 cm in length. Juvenile steelhead, 5–10 cm in length, were common

throughout upper Corralitos Creek above the Watsonville diversion dam, on 24 July 1962

(CDFG, unpubl. field notes of February–July 1962).

When the entire 24 km of the creek, including its headwater tributaries, was surveyed by

the CDFG in late August 1967 (Lollock 1968), the most favorable spawning areas were still

found between the Watsonville diversion dam and Shingle Mill Gulch. Small proportions of

upper Corralitos, Shingle Mill Gulch, and its tributary, Rattlesnake Gulch, also comprised

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suitable spawning grounds. Rearing habitat for juvenile steelhead was of particularly high

quality throughout the area upstream from the diversion dam; pools generally increased in size as

one proceeded downstream from the headwaters. The area below the diversion dam functioned

only as a migration corridor as channelization for flood control eliminated all steelhead

spawning and rearing habitat. Juvenile steelhead and/or rainbow trout were observed throughout

the survey area, except in the lowermost portion of the main stem Corralitos Creek. Fishing

pressure was high during the spring and early summer when the creek received 7,500 catchable

rainbow trout annually.

During an electrofishing survey on 28 July 1972 (R. Whaley, CDFG, unpubl. field corr.

to M. Johnson of 28 July 1972), the CDFG found juvenile steelhead and/or rainbow trout, 2.5–20

cm in length, in two sample sections of Shingle Mill Gulch. Trout, 2.5–15 cm in length, were

also captured in sample sections of Corralitos Creek both above and below the Shingle Mill

Gulch confluence, and in a section further downstream but still above the Watsonville diversion

dam. No fish were captured in the small Corralitos headwater tributary, Diablo Gulch. Smith

(1982a) found juvenile steelhead and/or rainbow trout in Corralitos Creek during 1972–74, both

above and below the confluence with Brown’s Valley Creek.

Some 350 yearling steelhead from Mad River Hatchery were planted in Corralitos Creek

in spring 1976 as mitigation for fish losses caused by an unspecified event.

In late fall 1981, the mean ± SD density of smolt-sized steelhead at nine Corralitos Creek

sites was 5.3 ± 6.2 trout/m, which was well above the county-wide average (derived from Smith

1982b). The mean ± SD of the site-specific mean lengths of these fish was 98 ± 4 mm SL,

which was also above average.

Corralitos Creek was surveyed by the CDFG during 21–23 June 1982, from near

Brown’s Valley Creek to about 0.6 km above the confluence with Shingle Mill Gulch (L. Turner,

CDFG, unpubl. memo. of 29 June 1982). The negative influence of fine sediment was still

evident in the creek. The only suitable spawning grounds within the survey area were found

between the confluences of Clipper and Shingle Mill gulches, where gravels were 5–7.5 cm in

diameter and 25 cm deep. Juvenile steelhead rearing habitat, in the form of pools and cover, was

adequate, although the pools were silted. Visually estimated abundances of young-of-the-year

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and yearling steelhead were very low downstream from Clipper Gulch (≤10/30 m and ≤ 2/30 m,

respectively) but high upstream from there, especially between Clipper and Shingle Mill gulches

(≤ 100+/30 m and ≤ 10/30 m, respectively). Eight logjams and four chutes or falls were located;

six of the logjams were classified as partial migration barriers. Improvements were subsequently

made at two sites to enhance fish passage. In addition, stream bed conditions, which were

degraded from sediment input from the January 1982 flood, were restored to normal through

natural processes by the end of 2 years, except in areas where land use resulted in chronic input

(Hecht 1984).

The Corralitos tributary, Brown’s Valley Creek, was surveyed by the CDFG in 1934.

Steelhead were present, and it was noted that natural propagation was very successful. Early

stocking records showed that the steelhead population was supplemented with 12,000 juveniles

in 1930, 18,000 in 1932, and 10,000 in 1933. The City of Watsonville maintained a diversion

dam with a fish ladder, about 3.2 km above Corralitos. Juvenile steelhead, 5–10 cm long, were

common in the stream above the dam when observed by the CDFG in August 1945. Steelhead

this size were also common below the dam in January 1961, in densities of 15–25 trout per pool.

Expanded densities were estimated at about 185–800 trout/km. Spawning and rearing habitat

was of high quality. Above the dam, juvenile steelhead densities were much lower; 2–5 trout per

pool, or about 60–185 trout/km. A local resident reported that “fair numbers” of steelhead

ascended the stream in winter, and that the fish ran far up the system when flows were great

enough. When surveyed by the CDFG between Gamecock Canyon Creek and the diversion dam

in January 1962, spawning gravels were limited and scattered, and juvenile steelhead (2.5–10 cm

long) were very scarce. Adults were reportedly taken by poachers. A fish kill of undetermined

cause below the diversion dam on 16 February 1964 revealed the presence of at least seven adult

steelhead, two “grilse”, and about 50 juvenile steelhead.

When Brown’s Valley Creek was surveyed by the CDFG in early August 1967 (Lollock

1968), flow became subterranean about 0.8 km above the confluence with Corralitos Creek.

Suitable spawning gravels were found in this dry section, which may have provided favorable

spawning areas for steelhead during the winter when surficial flow was continuous. Otherwise,

the highest quality spawning areas existed between the diversion dam and the mouths of the

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headwater tributaries, Ramsey Gulch and Gamecock Canyon Creek; limited spawning areas also

occurred in the tributaries. Rearing habitat for juvenile steelhead, in the form of pools and cover,

was adequate where perennial flow existed. Impassable cascades, created by bedrock and

boulders, existed in upper Gamecock Canyon Creek, and three logjams limited fish movements

on Ramsey Gulch, about 3.2 km upstream from the confluence with Brown’s Valley Creek. In

addition to the diversion dam, several pumps and wells diverted water from the creek system.

Juvenile O. mykiss existed throughout the survey area, including above the barriers in the

tributaries. Several 20 cm long trout were seen in Gamecock Canyon Creek, which were likely

resident rainbows. Smith (1982a) also found juvenile steelhead and/or rainbow trout in Brown’s

Valley and Gamecock Canyon creeks during 1972–74.

In late fall 1981, the mean ± SD density of smolt-sized steelhead at two sites in Brown’s

Valley Creek was 5.4 ± 4.9 trout/m, which was well above the county-wide average (derived

from Smith 1982b). The mean ± SD of the site-specific mean lengths of these fish was 105 ± 5

mm SL, which was also well above average. The density of smolt-sized steelhead at this time at

one site in each of Ramsey Gulch and Gamecock Canyon creeks, tributaries to Brown’s Valley

Creek, was 2.0 and 1.3 trout/m, respectively, both of which were well below average (derived

from Smith 1982b). Mean length in Ramsey Gulch, 119 mm SL, was well above average, while

that in Gamecock Canyon, 84 mm SL, was well below average.

The following are miscellaneous bits of information discovered for other Corralitos

Creek tributaries. Eureka Gulch was surveyed by the CDFG on 24 August 1945. The stream

contained high quality spawning areas, and juvenile steelhead were present. In late fall 1981, the

mean ± SD density of smolt-sized steelhead at three sites in Shingle Mill Gulch was 4.2 ± 0.8

trout/m, which was slightly above average (derived from Smith 1982b). The mean ± SD of the

site-specific lengths of these fish, 90 ± 6 mm SL, was below average.

Llagas Creek

The material on steelhead in this stream is currently being reviewed.

Pacheco Creek

Pacheco Creek is a tributary of the northeastern portion of the basin that enters the Pajaro

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River via Tequisquita Slough. The entire creek system was surveyed by the CDFG on 14 June

1957 (R. F. Elwell, CDFG, unpubl. stream survey report). Suitable spawning and rearing habitat

was observed throughout the survey area, although surface flow was interrupted in the

lowermost creek. According to local California Department of Forestry (CDF) personnel, flow

typically became interrupted in summer. The dam on the North Fork Pacheco Creek was the

only barrier to anadromous fishes seen. No water diversions or pollution were observed. Local

forestry personnel reported that juvenile steelhead/rainbow trout 7.5–20 cm in length occurred

throughout the live stream portions of the drainage, in addition to other native fishes such as

California roach and Sacramento sucker, and various introduced warmwater fishes. The local

warden reported that there was a strong steelhead run as far upstream as the north fork dam and

into the South Fork Pacheco Creek in 1952 and 1955. The stream supported a local sport fishery

for trout. The overall assessment made was that Pacheco Creek provided spawning and rearing

habitat for Pajaro River steelhead when sufficient flow occurred in winter to allow adult passage

through Tequisquito Slough. Elwell recommended that Pacheco Creek be managed primarily as

a steelhead spawning tributary.

The above survey was essentially repeated by the DFG on 19–20 December 1972 (R. R.

Johansen, CDFG, unpubl. stream survey report). The overall assessment of the creek system as a

steelhead production area was essentially the same, although some habitat degradation was noted

that was not apparent in 1957. Dairy waste and refuse from streamside ranches polluted the

lower half of the stream. Road construction on the South Fork Pacheco Creek and release of

sediment-laden water from Pacheco Dam on the north fork resulted in heavy siltation. Aquatic

insects were absent or occurred at very low densities and were dominated by black flies

(Simuliidae). Low insect densities may have reflected the combined effects of interrupted

stream flow in summer and siltation.

Johansen’s stream survey was preceded by a fish sampling survey conducted in the

mainstem Pacheco Creek and its tributary, Cedar Creek, on 14–15 December 1972 (R. R.

Johansen, CDFG, unpubl. memo. of 9 January 1973 to M. L. Johnson). Four stream sections,

from CDF’s Pacheco Ranger Station to the North Fork, were sampled with a single

electrofishing pass to determine fish species composition and size ranges. A total of 1.2 km of

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stream was sampled in which few fish (one California roach, and two sculpin) and few aquatic

insects were observed. The lack of fishes and invertebrates was attributed to dry stream

conditions the previous summer. Three wetted sections of Cedar Creek totaling 590 m sampled

in the same manner produced 22 juvenile steelhead/rainbow trout that averaged 12.5 cm and

ranged in length from 6.0 to 20.0 cm, thus likely representing at least age 0 and age 1 fish. Other

native species included California roach and Sacramento sucker; non-native green sunfish were

also captured. Apparently, perennial pools in headwater reaches such as Cedar Creek provided

suitable over-summering habitat for juvenile steelhead.

The local Fish and Game Warden summarized his observations of steelhead use of

Pacheco Creek system between 1958 and 1973 (W. I. Donahue, CDFG, unpubl. memo. of 10

January 1973 to R. Johansen). Donahue indicated that strong runs of adult steelhead were

associated with years of high rainfall, such as 1966 and 1968 (> 49 cm of precipitation), and that

poor runs occurred in low rainfall years such as 1971 (15 cm of precipitation). High quality

spawning and rearing habitat with perennial flow occurred upstream from Pacheco Dam on the

North Fork, but was unavailable to steelhead because of the dam. His impression was that South

Fork Pacheco Creek received modest use by steelhead spawners because of its high gradient and

lack of gravel for spawning, although it contributed perennial flow to the system. In contrast,

Cedar Creek was a relatively high use area for steelhead spawning. He also mentioned another

tributary, Harper Canyon, as having reports of steelhead use although he had not observed them

there. Finally, the mainstem Pacheco Creek supported trout when stream flow was sufficient.

Smith (1974, and summarized in Smith 1982) electrofished six locations in the Pacheco

Creek system during 1973–1974. Beginning in the upper system, the South Fork and its east

branch were sampled on 20 October 1973. Stream flow was interrupted to dry in the South Fork,

although there was continuous flow in the upper East Branch where water temperature was <

19ºC. Steelhead/rainbow trout occurred in isolated pools in the south fork, representing two

size/age classes at 7.5–10.0 cm SL and 21.5–24.0 cm SL. Steelhead/rainbow trout were highly

abundant in the East Branch and represented young-of-the-year at 6.0–13.0 cm SL and ≥ age 1+

fish up to 29.0 cm FL. Other native fishes and green sunfish occurred there also. The North

Fork above Pacheco Reservoir was sampled on 29 October 1973 where stream flow was

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interrupted but pools were available. No steelhead/rainbow trout were captured although other

native and introduced fishes were observed.

The uppermost main stem of Pacheco Creek was sampled at Rancho Los Laureles during

fall 1973 and late spring 1974. During 29–30 September 1973, juvenile steelhead were very

abundant in this area, with 10 to 30 at the head of each pool, and were most abundant in deep

riffles and runs. All trout were young-of-the-year which had grown well and averaged 14 cm SL

and ranged up to 20.0 cm SL (n = 69). Juvenile steelhead in this area averaged 16.5 cm SL when

sampled again on 26 December 1973, and all of them had apparently migrated from this area by

3 May 1974 when sampling occurred again. No 1974 year-class trout were observed at that

time.

The Pacheco tributary, Cedar Creek, was sampled at the stream gauging station on 3

November 1973. This area was at the lower limit of surface flow and steelhead/rainbow trout

were abundant: 37 trout were collected from five small pools, and these fish averaged 8.0 cm SL

(range: 6.5–9.5 cm SL).

The abundance of juvenile steelhead declined markedly at mainstem sampling stations

downstream from the confluence with Cedar Creek. Only one juvenile steelhead was collected

from a section at Casa de Fruta on 29 October 1973, a very fast growing young-of-the-year at

18.0 cm SL. Sacramento suckers and hitch dominated the catch. In isolated pools farther

downstream at the Highway 156 crossing, one juvenile steelhead at 7.5 cm SL was taken, among

a variety of other native and introduced fishes.

The uppermost main stem of Pacheco Creek was sampled at Rancho Los Laureles again

on 22 November 1975 (J. J. Smith and G. Scoppettone, unpubl. file memo. of 1 December 1975).

Electrofishing yielded 72 young-of-the-year steelhead that averaged 11.0 cm SL (range: 9.0–

16.5 cm SL) and that occurred at an approximate density of 4 trout/m of stream. Two age 2+

post-spawners at 40.0 and 41.5 cm SL were also collected. Scale analsysis indicated these fish

had spent one year in fresh water and one year in salt water before returning to fresh water to

spawn and where they remained. Although juvenile steelhead recruitment in the area sampled

was high, substantial production was apparently lost due to loss of flow farther downstream as a

result of decreased flow releases from Pacheco Reservoir. Maintenance of adequate releases was

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recommended to support the remaining population until winter rains began.

No juvenile steelhead were found in the creek at Rancho Los Laureles when sampled

during summer and fall 1978 (J. J. Smith, San Jose State University, unpubl. file memo.). The

lack of production in both 1976 and 1977 was attributed to drought conditions. Population

enhancement with stocked smolts in permanent pools below Pacheco Dam was recommended as

a management action. On 23 August 1978, the CDFG planted 9,975 steelhead (@ 209/kg) from

the Silverado Field Operations Base into the mainstem creek near the Pacheco Ranger Station.

The CDFG electrofished the stream at two sites on 16 December 1982 (J. Lorenzana,

CDFG, unpubl. file memo. of 20 December 1982): downstream from the Highway 152 crossing

on the uppermost main stem, and at the confluence of Cedar and Pacheco creeks. A total of 18

steelhead was collected at the two sites. Fish from the upper site were 18.0–23.0 cm SL and age

0+ based on scale analysis. The survey indicated steelhead recovery in Pacheco Creek,

following the 1976–1977 drought, and presence of steelhead in the mainstem creek upstream

from Casa de Fruta.

Additional observations of steelhead use of Pacheco Creek during the 1980s were also

available (J. J. Smith, San Jose, CA, unpubl. comment letter of 3 March 1992 to Santa Clara Co.

Advance Planning Office). Successful spawning and rearing occurred in 1983, based on the

observation of 1-year-old steelhead smolts in 1984. Successful spawning and rearing also

occurred in 1984, with direct observation of spawning adjacent to Casa de Fruta in March 1984.

Adult steelhead were observed while migrating in lower Pacheco Creek in 1985. Smith also

explained that steelhead use of the creek in the vicinity of Casa de Fruta is sensitive to overall

water year type. In average to wet water years, suitable flow and temperature conditions occur

in this stream reach for steelhead spawning and rearing, recognizing that the likelihood of these

conditions being met improves farther upstream in the drainage.

In summary, this sequence of surveys over nearly 30 years demonstrates the persistence

of steelhead in the Pacheco Creek system, with high recruitment in wet years, and little or no

recruitment in dry years. The importance of upper watershed refugia and maintenance flows as

available to get steelhead through drought events is also clear.

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Pescadero Creek

The Pajaro River tributary, Pescadero Creek, was surveyed by the CDFG in 1967

(Lollock 1968). This survey is currently being reviewed.

In late fall 1981, the mean ± SD density of smolt-sized steelhead at two Santa Clara

County sites was 2.0 ± 0.5 trout/m, which was well below the survey-wide average (derived

from Smith 1982b). The mean ± SD of the site-specific mean lengths of these fish was 127 ± 0

mm SL, which was the highest survey-wide average.

San Benito River and tributaries

The material on O. mykiss in this stream is currently being reviewed.

Uvas Creek

The material on steelhead in this stream is currently being reviewed.

Respini Creek Drainage Although no detailed historical information was discovered for Respini Creek,

Shapovalov and Taft (1954, p. 201) mentioned that the stream supported a steelhead run which

was smaller than those observed at Scott and Waddell creeks during the 1930’s–40’s.

San Lorenzo River DrainageThe San Lorenzo River has played a central role in the history of steelhead in Santa Cruz

County. Prior to 1905 and the enactment of law which set the daily bag limit at 50 trout,

fishermen would catch from 200 to 350 juvenile and adult steelhead per day in the San Lorenzo

and other local streams and sell them at Santa Cruz (Welch 1929). In 1905, the County of Santa

Cruz established a hatchery in the San Lorenzo drainage at Brookdale (Shebley 1922). An egg

collecting station was built on Scott Creek to provide eggs for the Brookdale Hatchery. The

Scott Creek facility was operated jointly by the California Fish Commission and the County.

Production from Brookdale was primarily used to enhance the steelhead populations of Santa

Cruz, San Mateo, Santa Clara, and Monterey counties, although fry were shipped elsewhere as

well. Both Brookdale Hatchery and the Scott Creek Egg Collecting Station were taken over by

the State of California in 1912. The work conducted at these facilities was apparently very

72

successful (Fish and Game Commission 1913). Heavy flooding in early 1940 severely damaged

the egg collecting station, and its operation was discontinued (D. Streig, Monterey Bay Salmon

and Trout Project, unpubl. report: History of fish cultural activities in Santa Cruz County with

reference to Scott and Waddell creeks). The Brookdale Hatchery continued production through

1953 hatching surplus eggs from CDFG hatcheries in northern California.

Regarding the natural distribution and abundance of steelhead in the San Lorenzo system,

in summer 1909 Snyder (1913) found juvenile steelhead/rainbow trout at each of six sites, from

the Kings Creek confluence in the upper drainage to Santa Cruz in the lowermost drainage. The

CDFG conducted a creel census on the San Lorenzo and tributaries during 1–2 May 1943, the

opening of the summer trout season (CDFG, unpubl. file data). This survey reflected the same

widespread distribution of juvenile steelhead/rainbow trout throughout the system. In addition to

in the main stem, catches were made in Zayante, Fall, Newell, Bear, Boulder, and Kings creeks.

The mean size of 592 trout seen in the 85 creels checked averaged 112 ± 20 mm (range, 76–178

mm), and the average catch rate was 2.87 ± 3.44 trout/h (range, 0–17 trout/h).

In an earlier survey conducted on 1 May 1939, the CDFG checked creels from Ben

Lomond to 1.6 km above Brookdale Hatchery (CDFG, unpubl. file data). Fifty-one anglers were

checked who had captured 105 marked steelhead that averaged 165 mm, and 406 unmarked

steelhead that averaged 127 mm. During 1–3 May 1942, 176 creels were checked which

contained 1,110 trout caught at a rate of 3.03 trout/h. These creel surveys indicated that the

harvest of large numbers of small juvenile steelhead continued to occur as of c. 1940.

In relation to these fishery assessment activities, from June 1938 through July 1939, the

CDFG supplemented the steelhead population in the San Lorenzo with 526,355 juveniles from

the Big Creek and Brookdale hatcheries. Of these, 7,046 were marked (L. Shapovalov, CDFG,

unpubl. memo. of 23 November 1954). During 1940–41, 11,080 marked, Mt. Whitney strain

rainbow trout were stocked in the river, and 538 marked, Mt. Shasta strain rainbow trout were

stocked during 1941–42.

By the 1940’s, fishery management at the San Lorenzo River had intensified in an

attempt to balance various fishery needs in the face of a growing local human population and

associated development. A CDFG document of late 1948 provided a snapshot view of the San

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Lorenzo and its steelhead/rainbow trout population at that time (Assistant Fisheries Biologist

[unsigned], CDFG, unpubl. memo. to G. I. Murphy of 14 December 1948). Adult steelhead

entered the river to spawn following the first fall rains in October and November. The run

typically peaked in January and continued through March and sometimes into June. Steelhead

used an estimated 125 km of stream for spawning in the main stem and tributaries. The stream

was managed for basically three fisheries: (i) the winter steelhead fishery in the lower main stem,

(ii) a summer trout fishery in tributaries below Boulder Creek, and (iii) an early summer only

trout fishery in the main stem and tributaries from Boulder Creek and above. Stream flow was

typically very low during August–November. There were many diversions for domestic water

supply. The river mouth remained open to the ocean throughout the year in all but below normal

water years.

As of 1951, the CDFG estimated that over 300,000 trout were caught each year in the

San Lorenzo system (R. M. Paul, CDFG, unpubl. memo. of 6 April 1951). These fish included

both juvenile steelhead/rainbow trout caught in the summer fishery, and adult steelhead in the

winter. CDFG stocking was limited despite the presence of the Brookdale Hatchery in the

system. Natural production was large enough to maintain the population and associated

fisheries. CDFG efforts to maintain the run were limited to pollution and barrier control. Sand

and gravel plants on Zayante Creek and their discharge of silt were a chronic pollution source,

although a court ruling stopped discharges in summer. Swimming pool drain water was an

occasional source of fish mortality.

During 1954–55, the CDFG (Pintler 1956) conducted electrofishing surveys immediately

before and after the opening of the summer trout season to determine (i) if maintaining open and

closed fishing areas of the river protected yearling steelhead from angling, and (ii) if planting of

catchable rainbow trout had a negative effect on the juvenile steelhead population. Of 36 km of

mainstem river, about 11 km above the Boulder Creek confluence were open to summer fishing,

while the 25 km below were closed. Near absolute counts of fish were made on four occasions

in nine 30.5 m sections in the open area, and in 10, 30.5 m sections in the closed area from late

April 1955, just prior to the opening of the trout season, through late July 1955. The average

density of yearling-size (>75 mm FL) steelhead in the open area decreased from 110 trout/100 m

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to 25 trout/100 m over the course of the study. There was a corresponding increase in average

density in the downstream closed area of 83 trout/100 m to 309 trout/100 m. Thus, there

appeared to be a net downstream movement of yearling steelhead into the closed area from late

April to late July. Pintler (1956) concluded that maintaining the downstream closed area did

indeed protect the yearling steelhead. During the same period, the average density of young-of-

the-year size (<75 mm FL) steelhead increased in both areas as emergence progressed; from 80

to 498 trout/100 m and 42 to 565 trout/100 m in the open and closed areas, respectively.

To get at the second question, two small plants of catchable rainbow trout were made in

the upstream area open to fishing: 2,504 on 9 June 1955 and 3,001 on 23 June 1955. None of

these fish was found in the closed area while electrofishing there, and their depletion in the

sampling program in the open area suggested they were readily harvested, thus minimizing the

opportunity for competition with juvenile steelhead. Creel censuses on the weekends following

these plants showed that, on average, about 82% of the catch was composed of planted trout.

Stomach content analysis of 96 catchable rainbow trout did not suggest predation on juvenile

steelhead. Although these results suggested little direct impact of planted catchable rainbows on

juvenile steelhead, Pintler (1956) concluded that a continued planting program should be

approached conservatively so as not to induce significant fishing mortality on the wild fish. For

example, he suggested that the opening of the summer trout season be delayed until 30 May to

provide a larger window of opportunity for yearling steelhead to escape to the downstream

closed area.

Following heavy flooding in December 1955, the lower San Lorenzo River within the

city of Santa Cruz was dredged and channelized to enhance flood control. The CDFG reported

concern over steelhead passage under low-flow conditions at the city’s diversion dam where

large rocks had been placed for reinforcement (S. C. Smedley, CDFG, unpubl. memo. of 16

March 1959). This document also mentioned that between 7,600 and 18,000 anglers fished the

river for steelhead annually, resulting in an estimated catch of between 1,350 and 5,650

steelhead.

The local CDFG warden reported that anglers caught about 200 adult steelhead in the San

Lorenzo lagoon on 1 December 1962 (CDFG, unpubl. field notes of 5 December 1962). About

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100 were taken on 2 December 1962. These steelhead weighed up to 2.7 kg but averaged only

about 0.7 kg. Angling was much slower on 5 December 1962 when only two steelhead were

observed in 2 h.

In 1965, the CDFG estimated the annual steelhead spawning run in the San Lorenzo

River at about 23,000 fish, based on the observations of local field personnel (California

Department of Fish and Game 1965).

The CDFG surveyed the mainstem San Lorenzo from headwaters to mouth during 15–18

September 1966. Spawning gravels were in suitable condition for steelhead use above Boulder

Creek, but were silted from there to the mouth. Siltation resulted from logging, road building,

grading, and sand plant operations throughout the drainage (see tributary information below),

and constituted 8% of the stream bottom in the mainstem San Lorenzo. Rearing habitat in the

form of pools and cover was present throughout the stream. There was a culvert barrier at the

Highway 9 crossing in the Waterman Gap area in the upper San Lorenzo, and a logjam barrier

about 2 km downstream. These barriers marked the upstream limit for steelhead spawners.

Many small pumps diverted water to vacation homes in summer, and the pumping facility at the

dam in Santa Cruz was a major year-round diversion. Juvenile rainbow trout were seen above

the culvert barrier, and juvenile steelhead occurred in high densities throughout the stream below

this point. Despite what appeared to be high steelhead production, the surveyor still cautioned

that unless sedimentation was curbed, spawning and rearing habitat for steelhead would be

seriously damaged.

In 1970, the CDFG estimated the abundance of juvenile steelhead from Waterman Gap to

the mouth of the San Lorenzo by electrofishing several randomly-selected 30.5 m reaches in 15

1.6-km sections (L. K. Puckett, CDFG, unpubl. memo. of 30 December 1971). Abundance was

estimated using the two-pass removal method. Juvenile steelhead abundance ranged from 48

trout/100 m in the upper river to 239 trout/100 m in SKM 16, and averaged 115 ± 45 trout/100

m among the 15 sections. Although abundance was lowest through the three uppermost km,

overall abundance did not vary significantly with SKM (p>0.15).

During the last week of April and first week of May 1972, a coalition of volunteers and

the CDFG rescued >500 adult steelhead from the lagoon of the San Lorenzo River (W.

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Greenwald, CDFG, unpubl. photo report, Operation Steelhead, of 31 May 1972). The steelhead

had entered the river to spawn but were unable to migrate upstream because of low flow. These

fish were trucked to holding ponds at Silver King Oceanic Farms, at the mouth of Waddell Creek

in Santa Cruz County, where they were spawned. The eggs were hatched at the CDFG hatchery

on the Mad River, Humboldt County where the young steelhead would be reared to yearlings

and then stocked back in the San Lorenzo and elsewhere.

During the mid-1950’s (Fisher 1957) and the first half of the 1970’s (M. L. Johnson,

CDFG, unpubl. memo. report of 22 November 1971; B. Snider, CDFG, unpubl. memo. of 5

September 1974; Johansen 1975; L. B. Boydstun, CDFG, unpubl. memo. of 2 September 1975),

the CDFG monitored fishing effort and catch in the San Lorenzo River winter steelhead fishery.

The objective of these studies was to develop a baseline against which to (i) evaluate the

contribution of future plants of hatchery-reared yearling steelhead to the fishery (Fisher 1957),

and (ii) evaluate proposed water development in the system (Johansen 1975). The catch rate

during the 1953-54 and 1954-55 seasons averaged 0.044 ± 0.013 trout/h (range, 0.035–0.053

trout/h). Catch rates from 1970-71 through 1974-75 averaged 0.026 ± 0.004 trout/h (range,

0.020–0.030 trout/h), and thus tended to be lower. This apparent difference was also reflected in

expanded estimates of total seasonal catch which averaged 3,770 ± 2,652 steelhead (range,

1,895–5,645 steelhead) during the mid-1950’s and 1,546 ± 544 steelhead (range, 1,035–2,368

steelhead) during the first half of the 1970’s. Johansen (1975) discussed the fact that habitat

degradation in the system, in particular siltation which had increased to an estimated 65% of the

stream bottom by 1972, along with the apparent decrease in catch rates and annual catches

suggested an actual decline in the steelhead population. He reiterated that logging and

associated activities, subdivision development, and water project construction were primarily

responsible for observed habitat degradation.

Johansen (1975) also collected size information on steelhead captured in the fishery.

Although the minimum steelhead size seen in the census was about 20 cm FL, only those >25 cm

FL were considered adults. In 1971-72 and 1972-73, angler-caught adults averaged 52 cm FL

and 47 cm FL, respectively. The combined season average was 49 cm FL. The largest adult

observed in the census was 81 cm FL, although an angler caught a 86.4 cm long fish at the river

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mouth on 19 November 1974 (Salinas Californian, 20 November 1974, p. 26).

On 26 April 1977, the CDFG rescued 114 emigrating adult steelhead from the forebay of

the Felton Diversion Dam on the San Lorenzo River (P. P. Chappell, CDFG, unpubl. memo. of 5

May 1977). An estimated 75–80% of the fish were spent, but few appeared moribund with

bacterial and fungal infections. The fish were released in the San Lorenzo lagoon.

The CDFG conducted a creel census on the upper San Lorenzo and several tributaries

during 26–28 May 1979, the opening of the summer trout season (M. L. Johnson, CDFG,

unpubl. memo. of 4 June 1979). This later opening date reflected Pintler’s (1956)

recommendation for a delayed season on the San Lorenzo to protect yearling steelhead (see

above). Angling pressure was light as only 18 anglers were seen during 90 h of census time over

the 3 d period. About 89% of the anglers were on the upper San Lorenzo and Fall Creek, where

100% of the fish seen were caught. The average catch rate, 0.96 ± 2.15 trout/h, was three times

lower than that seen in creel surveys conducted c. 1940 (see above). Only 17 juvenile steelhead

were seen in creels, and these fish averaged 140 ± 47 mm TL (n = 16). The relatively low use,

low catch rate, and small catch could be attributed to the delayed opening date and escapement

of yearling steelhead to the downstream closed area, a reduced steelhead population, the absence

of planted trout, or some other factor(s).

During the 1976-77 through 1978-79 steelhead seasons, the CDFG made fish counts at

the Felton Diversion Dam. As of 10 March 1977, 628 adult steelhead had moved up the San

Lorenzo (B. Graham, CDFG, unpubl. memo. of 10 March 1977), which was about 39% of the

total of 1,614 for the 1976-77 season (M. L. Johnson, CDFG, 17 September 1979). A minimum

of 242 adult steelhead passed during 1977-78, and 452 during 1978-79. These were considered

minimum counts as the trap was not operable all the time.

Johnson also mentioned that up to 25,000 yearling steelhead, when available, were

stocked annually in the San Lorenzo. A stocking summary in the CDFG stream survey file

showed that between 1963 and 1980, 230,716 juvenile steelhead were stocked in the San

Lorenzo, of which 95% were yearlings and 5% were young-of-the-year. In addition, from 1960

through 1972, the CDFG planted 231,403 catchable rainbow trout in the mainstem San Lorenzo

to support summer trout fishing. The stocking program was discontinued after 1972 because of

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an increase in private ownership and shrunken public access to the river (M. L. Johnson, CDFG,

unpubl. memo. of 13 November 1973).

In late fall 1981, the mean density of smolt-sized steelhead at 10 mainstem river sites was

980 ± 930 trout/100 m, which was the highest county-wide average (derived from Smith 1982b).

The mean of the site-specific mean lengths of these fish was 97 ± 10 mm SL, which was also

above average.

Bear Creek and tributaries

The San Lorenzo tributary, Bear Creek, was surveyed by the CDFG in November 1956.

The stream was described as an important spawning and rearing area for San Lorenzo River

steelhead. Logging operations were underway in the vicinity 9 km upstream from the mouth.

Barriers were present in the logging area, and silt and debris polluted the stream immediately

below this point. The stream contained adequate spawning and rearing habitat in the middle and

lower survey area. Juvenile steelhead were scarce above the logging area, but common below.

Local residents reported that the creek supported a substantial run of steelhead each year. The

Bear Creek steelhead population was supplemented with juvenile plants during 1940–47, and in

1956.

Bear Creek was briefly surveyed by the CDFG in January 1961. Spawning and rearing

habitats were in good condition. Natural propagation was highly successful as an abundance of

5–10 cm juvenile steelhead was observed, roughly estimated at 185–370 trout/km. Adult

steelhead reportedly spawned in the creek during the winter of 1960-61, and redds and 3–4 cm

long young-of-the-year were observed in high abundance near Elks Park on 19 April 1961. In a

related document from that time, it was mentioned that the CDFG had planted 6,000 catchable

rainbow trout in Bear Creek each summer, but that this practice had been discontinued.

The creek still consisted of high quality spawning and rearing habitat when surveyed by

the CDFG in July 1971. At least two age-classes of juvenile steelhead were observed in

abundance. Catchable-size trout were noted. Potential barriers and the upstream limit of trout

distribution were identified.

Cabrillo College students made abundance estimates of juvenile steelhead in Bear Creek

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during September–October 1972. Two to four reaches within each of six 1.6-km sections were

sampled by electrofishing using the two-pass removal method of population estimation.

Densities over the 10 km study area ranged from 99 to 708 trout/km, and averaged (± SD) 612 ±

412 trout/km.

About 60 steelhead redds were observed in lower Bear Creek in June 1980 (L. Turner,

CDFG, unpubl. file report of 30 July 1980). Steelhead fry were abundant, and individuals

ranging in length from 15 to 35.5 cm were common from the creek mouth to a series of

waterfalls located about 0.3 km below the confluence with Shear Creek. These falls were judged

to be the upstream limit for adult steelhead immigration. A few fry were observed between the

falls and Shear Creek; these fish may have been the progeny of resident rainbow trout inhabiting

the stream above the barrier falls. The Bear Creek tributary, Deer Creek, contained an

abundance of steelhead fry and older trout (10–30.5 cm long) from its mouth up to a permanent

waterfall barrier. Again, above this point, trout density was low and may have represented an

isolated resident rainbow trout population.

In late fall 1981, the mean ± SD density of smolt-sized steelhead at three sites in Bear

Creek was 3.9 ± 2.3 trout/m, which was about the county-wide average (derived from Smith

1982b). The mean ± SD of the site-specific mean lengths of these fish was 102 ± 6 mm SL,

which was above average.

Bear Creek was generally in good condition following the heavy storms of January 1982,

as determined by a CDFG survey in May 1982 (L. Turner, CDFG, unpubl. memo.). Redds were

observed in the lower stream. Steelhead fry were present but apparently in low densities. Older

trout, 15–30.5 cm long, were common in deep pools. Several barriers were identified.

Boulder Creek and tributaries

Both age 0+ (<7.5 cm) and older juvenile steelhead (>7.5 cm) were captured during a

CDFG electrofishing survey in a 61 m reach of the San Lorenzo tributary, Boulder Creek, in

May 1954. When surveyed again by the CDFG in November 1956, spawning areas were rated

as lacking to fair, rearing habitat was especially good in the middle and lower sections of the

stream, and both young-of-the-year (5–7.5 cm) and older juvenile steelhead (7.5–20 cm) were

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observed. Six partial or complete barriers were identified, but no diversions were noted. It was

also noted that the Boulder Creek steelhead population had been supplemented with juvenile

plants during 1940–47.

By the tine of the next CDFG survey in August 1966, habitat degradation due to siltation

was becoming an increasing problem in the stream, although suitable spawning and rearing

habitat was still observed. The abundance of juvenile steelhead (4–10 cm) was noted as low, and

average density was estimated at about 1 trout/m. The condition of the stream was apparently

similar when surveyed by the CDFG in July 1971; spawning and rearing habitat was noted as

good below Bracken Brae Creek where the greatest abundance of young-of-the-year and yearling

steelhead and resident rainbow trout was seen. Several potential or full barriers were noted.

A total of 19 partial and full barriers, including logjams, were identified by the CDFG in

June 1980 (L. Turner, CDFG, unpubl. file report of 31 July 1980). Low densities of juvenile

steelhead were observed in the lower and mid-creek sections, with 20–30.5 cm fish common in

pools. At least some of these larger fish were probably resident rainbow trout. The distribution

of suitable spawning substrate was apparently much more restricted than in previous surveys;

two steelhead redds were seen.

In late fall 1981, the mean ± SD density of smolt-sized steelhead at four sites was 3.4 ±

2.7 trout/m, which was slightly below average (derived from Smith 1982b). The mean ± SD of

the site-specific mean lengths of these fish was 105 ± 4 mm SL, which was well above average.

The stream was judged to be in fair condition by the CDFG in May 1982 (L. Turner,

CDFG, unpubl. memo. of 18 May 1982). Spawning areas were scattered and often cemented

with silt in the lower stream. The best spawning areas were now located above Hare Creek

where numerous steelhead redds were observed. This area also contained an abundance of

steelhead fry. Siltation was still noted as a problem, especially below the Boulder Creek Country

Club, and several partial and complete barriers were identified.

The effect of sedimentation in the creek was investigated by the CDFG in August 1982,

in relation to a construction project (R. C. Benthin, CDFG, unpubl. file report of 2 September

1982). The density of both invertebrates and juvenile steelhead was clearly lower downstream

from the construction site, where the percentage of fine material in the substrate was higher than

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above the construction site.

In late fall 1981, the density of smolt-sized steelhead at one site in Jamison Creek, a

Boulder Creek tributary, was 2.6 trout/m, which was below average (derived from Smith

1982b). The mean length of these fish was 94 mm SL, which was slightly below average. The

upper portion of this stream was choked with logging debris when observed by the CDFG in

June 1980 (L. Turner, CDFG, unpubl. file report of 31 July 1980). A few juvenile steelhead

and/or resident rainbows up to 25 cm in length were observed in the lower creek.

Branciforte Creek and tributaries

Branciforte Creek, a tributary to the San Lorenzo River, was surveyed by the CDFG in

October 1956. Spawning grounds for steelhead were practically nonexistent in Branciforte

Creek due to extensive sedimentation, but apparently there were some suitable areas in tributary

streams. Rearing habitat was also of generally poor quality. Several barriers were identified,

some of which were permanent blockages to upstream migrants. Juvenile steelhead were very

scarce. The stream was stocked with juvenile steelhead and catchable resident rainbow trout

from 1940 to 1956.

Branciforte Creek was surveyed briefly by the CDFG in December 1960; no adult or

juvenile steelhead were observed. During another brief survey on 3 February 1961, two adult

steelhead (about 30 and 61 cm long) were seen spawning on a riffle at the downstream end of a

small pool. No juveniles or other adults were observed.

The CDFG surveyed Branciforte Creek from its mouth to its headwaters, a distance of

about 14.5 km, in mid-August 1966. Although regarded as an insignificant steelhead stream in

earlier surveys, the creek was now described as an important spawning and rearing area for San

Lorenzo steelhead and coho salmon. Suitable spawning gravel was available for steelhead, but

siltation was still cited as a growing problem. Rearing habitat was apparently best in the middle

and upper stream areas. Despite a somewhat improved habitat rating, juvenile steelhead (4–7.5

cm long) still occurred only in low densities, at an average of about 2 trout/30 m.

By the time the creek was surveyed by the CDFG in August 1971, siltation and septic

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tank leakage had ruined historic spawning and rearing areas below Jarvis Road, above which

there was little steelhead habitat. Juvenile steelhead were present throughout the stream, but

only in very low densities (<3 trout/30 m).

During a CDFG barrier survey in July 1980, juvenile steelhead were seen again only in

low densities. In addition, about 80 steelhead redds were observed in silty substrate, about 0.3

km downstream from the confluence with Granite Creek. It was noted that silt covered the

substrate along the entire observed length of stream, to above the confluence with Crystal Creek.

The condition of Branciforte Creek was largely unchanged when surveyed by the CDFG

in June 1982 (L. Turner, CDFG, unpubl. memo. of 7 July 1982). Juvenile steelhead were scarce,

and age 0+ trout were concentrated at a few locations in the lower stream. Numerous dams

appeared to have inhibited the flushing of silt from the system, rendering the stream unsuitable

for salmonid production.

The Branciforte Creek tributary, Carbonera Creek, was surveyed by the CDFG on 16

October 1956, from the mouth to Zanze’s, 5.6 km upstream, where there was a 12 m high

bedrock waterfall barrier. There was also a logjam barrier in the lower stream, near the county

hospital. Although spawning gravels were present throughout the survey area, they were of the

highest quality in the mid-section, above the logjam. Rearing habitat was adequate, in terms of

pools and shelter. Several diversions were observed, which were adequately screened. Siltation

was a pollution problem in a 0.8 km mid-section reach where logging had occurred; the stream

was clogged with logging debris there as well. Juvenile steelhead, 5–10 cm long, were common

throughout the survey area. The fish were relatively abundant in the mid-section and scarcer in

the upper and lower sections. Overall, the stream was rated as the most important steelhead

spawning and rearing tributary to Branciforte Creek. The steelhead population was

supplemented with a plant of juveniles in 1953.

When surveyed again by the CDFG in August 1966, the condition of Carbonera Creek

was largely unchanged, although the overall abundance of juvenile steelhead was apparently

lower. In the lower stream, the estimated density was 100 trout/30 m. These fish were 4–5 cm

long. No fish were seen in the mid-section of the survey area, and few were seen further

upstream.

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By the time of the next CDFG survey on 21 September 1974, siltation, as a result of

logging operations, had become a greater problem. Most spawning areas were apparently

degraded.

O. mykiss, about 5–30.5 cm in length, occurred in low densities throughout the creek,

from the mouth to the bedrock waterfall, when surveyed for barriers by the CDFG on 11 August

1980. Several partial and full barriers were identified, and a fish kill was observed in the lower

stream which included 32 steelhead.

In late fall 1981, the mean ± SD density of smolt-sized steelhead at three sites was 0.5 ±

0.5 trout/m, which was the lowest county-wide average (derived from Smith 1982b). The mean

± SD of the site-specific mean lengths of these fish was 95 ± 9 mm SL, which was very near

average.

Carbonera Creek was surveyed up to the bedrock waterfall by the CDFG in late June

1982, following the heavy storms of January 1982 (L. Turner, CDFG, unpubl. memo. of 8 July

1982). Spawning gravels were still best in the middle portion of the survey area, and the deepest

rearing pools were in the middle and upper sections. Age 0+ O. mykiss were present in the

middle and lower sections, but in low densities. Larger trout, 10–25 cm long, were observed in

the deep pools in the upper section. Overall, the stream was in fair condition. No other major

barriers were present besides the bedrock waterfall. Silting was moderate.

A small Carbonera Creek tributary, Camp Evers Creek, was surveyed by the CDFG in

January 1985 (W. Strate, CDFG, unpubl. memo. of 9 January 1985). The stream was highly

degraded due to a lack of riparian vegetation and siltation, and no fishes were seen. However, no

barriers were present and with habitat improvement, the creek was judged to have potential as a

steelhead production area.

Clear Creek

The San Lorenzo tributary, Clear Creek, junctions with the San Lorenzo River at

Brookdale. When surveyed by the CDFG in January 1957, the stream was described as

unimportant for steelhead because a permanent bedrock barrier at the mouth precluded upstream

migration of adult spawners. No fish were observed in the creek, despite plantings of hatchery-

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reared resident rainbow trout in 1945 and 1947. Nor were any fish seen in the lower stream in

October 1959. During a CDFG barrier survey in mid-May 1980, three resident rainbow trout,

20–25 cm long, were observed in lower Clear Creek. The creek mouth still contained a complete

migration barrier, and other barriers were identified upstream.

Fall Creek

The San Lorenzo tributary, Fall Creek, was surveyed by the CDFG in June 1956. Natural

reproduction was rated as poor for that year; juvenile steelhead were observed only in low

densities up to an impassable waterfall, about 5 km upstream from the mouth. In the lowermost

stream area, the density of 2.5–4 cm long juveniles was about 5–6 trout/pool. Juvenile steelhead

were also observed in lower Fall Creek in October 1959.

In an August 1966 CDFG survey, it was indicated that about 11 km of Fall Creek was

available to steelhead for spawning and rearing. Spawning gravels were abundant throughout

most of the stream, and rearing habitat was at least adequate. However, the diversion dam for

the community of Felton’s domestic water supply acted as a barrier to adult upstream migration.

Few juvenile steelhead were seen above the dam; below, they occurred at a density of about 15–

20 trout/30 m. At the time of this survey, the CDFG planted about 1,000 catchable rainbow trout

per week during the summer trout season. Overall, the stream was judged to be in excellent

condition.

Abundance estimates of juvenile steelhead in 3.2 km of Fall Creek in 1970 were 77

trout/100 m in the lowermost 1.6 km, and 52 trout/100 m in the contiguous 1.6 km upstream (L.

K. Puckett, CDFG, unpubl. memo. of 30 December 1971). The CDFG observed two adult

steelhead in the stream on 20 November 1973.

In October 1975, the CDFG determined the abundance, size, and biomass of juvenile

steelhead in four 30 m sections in Fall Creek (P. P. Chappell, CDFG, unpubl. memo. of 13

November 1975). The average abundance was 2,842 trout/km or 8,028 trout/ha, and average

biomass was 33.5 kg/ha. Average trout size was about 68.5 mm FL.

The CDFG captured juvenile steelhead, 5–20 cm long, by electrofishing in early June

1978 (D. M. Eimoto, CDFG, unpubl. memo. of 11 July 1978). Steelhead fry were seen both

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above and below the Felton water filter plant.

The CDFG conducted a survey of barriers in Fall Creek in April 1980. A total of 15

partial and complete barriers, including logjams, was identified in the main creek, and the

tributaries, Bennett Creek and South Fork Fall Creek, were completely impassable for upstream

migrating fish due to waterfalls and slash in the streams from old logging operations. By this

time, fish passage problems at the Felton diversion dam had been solved by installation of a

fishway. Steelhead fry were common in Fall Creek from its mouth to above the confluence with

the south fork, after which fry became scarce. Three adult steelhead were seen in a pool in the

lower stream, and one 20 cm trout further upstream.

In late fall 1981, the mean ± SD density of smolt-sized steelhead at two sites was 3.9 ±

2.3 trout/m, which was just about average (derived from Smith 1982b). The mean ± SD of the

site-specific mean lengths of these fish was 93 ± 2 mm SL, which was somewhat below average.

Fall Creek was surveyed again by the CDFG in April 1982, following the January 1982

storms. Spawning habitat apparently remained intact from the mouth to the confluence with the

south fork. Above this point, siltation as a result of two major landslides had degraded both

spawning and rearing habitat. Several migration barriers were identified. Eight adult steelhead

were seen in the lower stream area.

In November 1983, a composite electrofishing sample from five sample reaches of Fall

Creek (4–11.5 m) produced the following abundance estimates: 0.70 age-0+ trout/m and 0.46

age-1+ trout/m. The mean standard length of 0+ and 1+ fish was 61.0 mm and 109.2 mm,

respectively.

Kings Creek

The San Lorenzo headwater tributary, Kings Creek, was surveyed by the CDFG in 1956,

1966, 1971, 1974, and 1980 (Smith 1982b), although the CDFG file containing these survey

reports was not discovered. In late fall 1981, the density of smolt-sized steelhead at one site was

3.3 trout/m, which was below average (derived from Smith 1982b). The mean length of these

fish, 84 mm SL, was also below average.

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Newell Creek

Newell Dam forming Loch Lomond Reservoir on the San Lorenzo tributary, Newell

Creek, was built during 1962-63. The dam blocks steelhead access to the upper creek. The

CDFG stocked the reservoir with 611,729 catchable rainbow trout from 1963 through 1976. In

late fall 1981, the mean ± SD density of smolt-sized steelhead at three sites was 4.3 ± 2.0

trout/m, which was above average (derived from Smith 1982b). The mean ± SD of the site-

specific mean lengths of these fish was 100 ± 5 mm SL, which was also above average.

Zayante Creek and tributaries

The San Lorenzo tributary, Zayante Creek, was surveyed from its mouth to headwaters

for a distance of 13 km, by the CDFG in October 1956. This creek was described as one of the

best steelhead spawning and rearing areas in the entire San Lorenzo drainage. Spawning gravels

were in excellent condition in the upper stream, but became increasingly silted as one progressed

downstream. Rearing habitat was also of higher quality in the middle and upper stream areas.

Correspondingly, juvenile steelhead were scarce to common in the lower stream up to Quail

Hollow Road, and increased in abundance further upstream. There were 14 partial and four

complete logjam barriers, and several unscreened diversions. Siltation was cited as the main

pollution problem, the sources being eroded materials from a logged area in the upper watershed,

and a sand plant in the lower stream area. The steelhead population was supplemented with

plants of hatchery-reared juveniles from 1940 to 1947.

The lowermost 2.4 km of the South Branch Zayante Creek were also surveyed by the

CDFG in October 1956. High quality spawning and rearing habitats for steelhead were

observed. Juvenile steelhead, 7.5–10 cm long, were common to abundant in the lower section of

the survey area, and scarce in the upper section. Three complete logjam barriers were identified,

and there was a natural bedrock barrier about 2.8 km upstream from Zayante Creek. No

diversions or signs of pollution were seen.

On 3 February 1961, the CDFG observed seven adult steelhead resting in pools between

Quail Hollow bridge and Lompico Creek. A steelhead redd was seen just upstream from the

confluence with Lompico Creek on 13 April 1961. The CDFG surveyed lower Zayante Creek,

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from the mouth to the confluence with Lompico Creek, in April 1964. Siltation was still a

chronic problem in this portion of the stream, especially in the lowermost 2.4 km where O.

mykiss fry occurred at an approximate density of 375 fish/km. Above this area, 188 trout were

counted which ranged in length from 5 to 46 cm, and averaged about 10 cm. Total abundance in

this upper area was estimated at 400–500 fish, consisting of a mixed migratory and resident

rainbow trout stock. Additional stocking of O. mykiss in Zayante Creek occurred from 1956 to

1960. Fishing pressure was noted as heavy.

The upper Zayante Creek headwaters were also surveyed by the CDFG around this time.

Siltation had apparently become a problem in this area since the 1956 survey. The survey

section included a 9 m bedrock barrier. O. mykiss occurred in relatively lower densities above

the barrier, and these fish were likely resident rainbow trout. Young-of-the-year, about 5 cm

long, were abundant, and older trout were common with numerous individuals up to 28 cm. As

one progressed downstream from the barrier, juvenile steelhead density increased from about

100 trout/km to about 260 trout/km.

The adult steelhead run in Zayante Creek as of 1968 was estimated by the CDFG at about

800 fish, although the method used to attain this estimate was not described. Juvenile steelhead

sizes and densities were measured in the lower creek from Quail Hollow Bridge to just above the

confluence with Lompico Creek on 18 June 1968 (M. L. Johnson, CDFG, unpubl. file report of

10 July 1968). Fish were sampled by use of electroshocking in 30–60 m long sections, and

abundances were determined with the two-pass removal method of population estimation.

Densities in three mainstem sections were 40 trout/30 m (below Lompico Creek), 275 trout/30 m

(above Lompico Creek), and 25 trout/30 m (Quail Hollow Bridge). Most fish captured were

young-of-the-year and mean lengths in each section were about 37 mm, 55 mm, and 48 mm,

respectively. No fish were captured in lower Lompico Creek, and in a headwaters section, trout

density was low (4 trout/30 m) but mean length (114 mm), and thus age, of these fish was

greater. The largest individual measured 160 mm.

In October–November 1970, the CDFG determined juvenile steelhead lengths, weights,

and abundances in the uppermost 9.7 km of Zayante Creek (L. K. Puckett, CDFG, unpubl.

memo. of 25 June 1971). Fish were sampled by use of electroshocking in 10 30-m sections, and

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abundances were determined with the two-pass removal method of population estimation. The

average section density was about 61 trout/30 m, and total abundance was estimated at 19,100

trout (95% C.L., 15,900–22,360). The number and percent of age 0+, 1+, and 2+ trout was

18,031 (94.4%), 1,012 (5.3%), and 57 (0.3%), respectively. Age 0+ steelhead ranged in length

from about 4 to 11 cm, and the mode in their length-frequency distribution was between 5 and

7.5 cm. Age 1+ steelhead ranged in length from about 11 to 15 cm, and the single age 2+ trout

captured was about 22 cm. Based on age-class specific survival rates to adulthood from

Shapovalov and Taft (1954), the number of adults produced from the juvenile population

observed in fall 1970 would be about 540 adult steelhead2 (95% C.L., 450–630). The total

biomass of the juvenile population was estimated at 95.5 kg, or 9.8 kg/km.

Juvenile steelhead samples were taken on 19–20 January 1977 by electrofishing three 30-

m sections in lower Zayante Creek (CDFG, unpubl. memo. of 27 January 1977). Mean (± SD)

steelhead length in the composite sample was 8.8 ± 2.6 cm (n = 82; range, 4.8–15.2 cm). Age 1

fish were roughly <9.5 cm long and comprised 62% of the sample, while age 2 fish were ≥ 9.5

cm long and comprised 38% of the sample.

During the 1978-79 spawning season, 53 redds were located in Zayante Creek; 34 (64%)

were downstream from a proposed dam site near the confluence with Mountain Charlie Gulch,

19 (36%) were upstream from the dam site (D. W. Kelley, Zayante Creek Fish and Wildlife

Investigation Report for the Month of April 1979, 9 May 1979). Adult steelhead had migrated

into Zayante Creek during high flows in February 1979. Moving sand was identified as a

potential problem for embryo survival in the redd, although some survival occurred as evidenced

by the presence of emergent steelhead fry.

In late fall 1981, the mean ± SD density of smolt-sized steelhead at three sites was 7.2 ±

7.0 trout/m, which was relatively high (derived from Smith 1982b). The mean ± SD of the site-

specific mean lengths of these fish was 89 ± 3 mm SL, which was below average.

2. In a reworking of Puckett’s data, D. Dettman (unpubl. file report attached to letter of D. W. Kelley, 9 May 1979) arrived at a lower estimate of 153 returning adult steelhead.

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In 1984, removal of a bedrock waterfall barrier allowed steelhead access to an additional

8 km of stream habitat in the Zayante Creek system.

The Zayante Creek tributary, Bean Creek, was surveyed by the CDFG in October 1956.

The stream was noted as one of the better steelhead production areas in the San Lorenzo River

drainage. High quality spawning grounds were apparently abundant throughout the 11 km

survey area, and rearing habitat seemed adequate. Logjams created complete migration barriers

at two locations in the middle and upper survey area. Juvenile steelhead, 5–7.5 cm in length,

were abundant throughout the survey area. The largest trout seen were about 15 cm long. It was

also noted that hatchery-reared juvenile steelhead and resident rainbow trout had been stocked in

Bean Creek during 1940–43 and 1950–51.

Three pairs of adult steelhead were seen spawning on a riffle near the Salvation Army

camp bridge on 1 March 1957.

Juvenile steelhead were observed in Bean Creek in June 1962 during a CDFG spot check.

The stream was surveyed from the mouth to its headwaters (14.5 km) by the CDFG in

September 1966. By this time, siltation had reduced spawning areas for steelhead; there were

short reaches of loose gravel in the middle stream area, but none was found in the lower stream

area. Discharge from sand processing plants was the main silt source. Pools were very shallow,

but shelter was adequate, and migration barriers were identified, the uppermost being a bedrock

waterfall which marked the upstream limit for migrating fish. The lower stream contained

juvenile steelhead (5–7.5 cm in length) at a density of about 10–15 trout/30 m. No fish were

observed in the upper stream area.

Abundance estimates were made by electrofishing several randomly-selected 30 m

reaches in six 1.6-km sections of Bean Creek in 1970, using the two-pass removal method (L. K.

Puckett, CDFG, unpubl. memo. of 30 December 1971). Juvenile steelhead abundance ranged

from 24 trout/100 m at the mouth to 74 trout/100 m in the upper stream, and averaged 53 ± 17

trout/100 m among the six sections.

When surveyed by the CDFG in July 1971, the siltation problem, especially in lower

Bean Creek, was apparently alleviated. Spawning and rearing areas were present, and in good

condition, from the mouth to above Glenwood. Juvenile steelhead, including young-of-the-year,

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were abundant.

The mean (± SD) length of juvenile steelhead electrofished at two stations in Bean Creek

on 13 October 1973 was 7.1 ± 1.4 cm; lengths ranged from 4.6 to 13.7 cm (derived from unpubl.

CDFG data). So, juveniles were mostly age 0+, although a few 1+ trout were also present. Five

adult steelhead (38–50 cm long) and one 25-cm male O. mykiss were observed in a 122 m reach

of Bean Creek near Mt. Herman on 20 November 1973.

Erosion/siltation and barrier problems in Bean Creek were identified by the CDFG in

early June 1980. Young steelhead, mostly 2.5–5 cm but up to 25 cm in length, were observed

from the mouth to above Camp Redwood Glen. Six steelhead redds were seen between

MacKenzie Creek and Camp Redwood Glen (L. Turner, CDFG, unpubl. memo. of 5–8 June

1980).

In late fall 1981, the mean ± SD density of smolt-sized steelhead at four sites was 3.1 ±

2.9 trout/m, which was slightly below average (derived from Smith 1982b). The mean ± SD of

the site-specific mean lengths of these fish was 98 ± 5 mm SL, which was above average. The

density of smolt-sized steelhead at this time at one site in Lockhart Gulch, a Bean Creek

tributary, was 1.0 trout/m, which was well below average (derived from Smith 1982b). The

mean length of these fish was 119 mm SL, and thus well above average.

The CDFG surveyed Bean Creek in April 1982 following the heavy storms in January

1982. Steelhead access was blocked by numerous logjam and debris dams, and spawning areas

were very limited due to extensive siltation. Some young-of-the-year steelhead were observed.

Another Zayante Creek tributary, Mountain Charlie Gulch, contained numerous juvenile

steelhead at its mouth when surveyed by the CDFG in October 1959. Smith (1982b) also noted

this creek as a productive spawning tributary for steelhead, but did not sample it.

San Vicente Creek Drainage The San Vicente Creek steelhead population was supplemented by the CDFG with a total

of 71,000 hatchery-reared juveniles during 1930–39. As a comparative measure of adult run

size, Shapovalov and Taft (1954, p. 201) mentioned that the San Vicente steelhead run was

smaller than those observed at Scott and Waddell creeks during the 1930s–1940s. Naturally

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propagated juveniles (7.5 cm in length) were seen in the stream by the CDFG in August 1960.

In March 1962, both adult and juvenile steelhead were observed below a landslide which had

temporarily blocked the stream. The stream and its drainage area were developed considerably

during the late 1960s and early 1970s; development activities substrate extraction, water

diversion and/or impoundment, and logging.

In late fall 1981, the mean ± SD density of smolt-sized steelhead at six stream sites was

4.7 ± 2.3 trout/m, which was above the county-wide average (derived from Smith 1982b). The

mean ± SD of the site-specific mean lengths of these fish was 88 ± 5 mm SL, which was below

average.

In July 1985, the CDFG rescued a 79 cm, 5-year-old adult steelhead from San Vicente

Creek and transferred it to the mouth of Scott Creek. An approximately 1.6 km section of the

creek, above the Pfyffer diversion, was surveyed by the CDFG on 26 June 1985 (D. Marston,

CDFG, unpubl. memo. of 27 June 1985). Unembedded spawning gravel was abundant, and

young-of-the-year steelhead juveniles were also abundant. Some yearlings were seen in larger

pools. Screened diversions were present, and some siltation was occurring from the washing out

of temporary dams, and from bank erosion. Fish passage was rated as good, and rearing habitat

for juvenile steelhead was excellent.

An adjacent downstream section of San Vicente Creek was surveyed in early July 1985

(D. Marston, CDFG, unpubl. memo. of 3 July 1985). Suitable spawning gravels were present

throughout this 2 km section, and young-of-the-year steelhead were abundant (about 700 seen).

One adult was also observed. Potential barriers were identified.

The lower portion of the stream was surveyed by the CDFG in late July 1985 (D.

Marston, CDFG, unpubl. memo. of 25 July 1985). High quality spawning substrate was not

present in this area, but numerous young-of-the-year and yearling steelhead were observed there.

Rearing habitat appeared adequate. A diversion dam acted as a temporary migration barrier,

and there was an unscreened off-stream diversion channel which entrained juvenile steelhead.

There was also some pollution in this lower stream area, located within the town of Davenport.

So, despite considerable development, San Vicente Creek was still a highly productive steelhead

stream.

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Mill Creek. In the San Vicente tributary, Mill Creek, in late fall 1981, the mean ± SD

density of smolt-sized steelhead at two sites was 3.4 ± 2.6 trout/m, or slightly below average

(derived from Smith 1982b). The mean ± SD of the site-specific mean lengths of these fish was

79 ± 0 mm SL, which was the lowest county-wide average.

Scott Creek Drainage Estimates of the number of females in the spawning runs during 1905–40 (Fig. 12) are

currently being developed from egg collection and fecundity data (p. 148 in Shapovalov and Taft

1954 for length-fecundity relationship of Scott Creek steelhead).

Early fish planting records for Santa Cruz County showed that the Scott Creek steelhead

population was supplemented with 121,000 juveniles in 1913 and 148,000 in 1915 (D. Streig,

Monterey Bay Salmon and Trout Project, unpubl. report: History of fish cultural activities in

Santa Cruz County with reference to Scott and Waddell creeks). Planting data for other years

during 1905–1929 were either missing or were composites for all of Santa Cruz County and,

thus, did not specify the number of juvenile steelhead stocked in Scott Creek alone. These plants

were of Scott Creek steelhead cultured at either the Big Creek or Brookdale hatcheries, except in

1928 when 152,000 steelhead from the Mt. Shasta Hatchery were planted in Santa Cruz County

because furunculosis (Aeromonas salmonicida) destroyed most of the production at the local

hatcheries.

CDFG fish stocking records from the 1930’s showed that the population was

supplemented with 8,000 juvenile steelhead in 1930; 65,000 in 1932; 42,340 in 1933; 37,764 in

1934; 5,614 in 1935; 115,000 in 1936; 174,986 (@ 37–1,340/kg) in 1938; and 221,034 (@ 44–

4,233/kg) in 1939. All these plants comprised Scott Creek steelhead hatched at Big Creek or

Brookdale. No specific Scott Creek planting record was discovered for 1940 when the Big

Creek Hatchery was closed (Leitritz 1970; see Big Creek, below), but all steelhead planted in

Santa Cruz County that year were of Scott Creek origin. Juvenile steelhead planted in Santa

Cruz County in 1941 were from eggs of Prairie Creek Hatchery origin which were hatched at

Brookdale. The hatchery operation at Brookdale continued until 1953 (Leitritz 1970; see San

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Lorenzo River Drainage) supplied with surplus eggs from other CDFG hatcheries in northern

California. In a CDFG file letter of 27 May 1948, it was indicated that 6,000 resident rainbow

trout (@ 705 fish/kg) would be stocked during the 1948 season. It was also mentioned that

stocking had not been carried out in Scott Creek in 1947. No records have been found which

specify plants made in Scott Creek or other Santa Cruz County streams during the remainder of

the period, 1942–53 (D. Streig, Monterey Bay Salmon and Trout Project, unpubl. report: History

of fish cultural activities in Santa Cruz County with reference to Scott and Waddell creeks).

Consult Dayes (1987) for further information pertaining to the history of fish culture and related

activities in Santa Cruz County.

When Scott Creek was surveyed by the CDFG in 1934, it was already apparent that the

stability of the stream environment was being impacted by water extraction. Twelve diversions,

which consisted of pumps with screened intakes, were counted. The surveyor indicated in the

report that the creek dried up in two major reaches due to the effects of pumping: from the mouth

to 3.2 km upstream; and from Seaside School to the mouth of Big Creek, for a distance of about

2.4 km.

Of course, the Scott Creek drainage at that time was still very important for both the

natural and artificial production of steelhead and coho salmon in Santa Cruz County. Abundant

spawning grounds were available to anadromous salmonids up to a 6 m waterfall in the

headwaters (distance upstream not indicated in this survey). Angling pressure for these fishes

was heavy upstream from the confluence with Mill Creek, the only portion of Scott Creek where

fishing was allowed.

On 30 September 1942, the CDFG observed several schools of 200–400 juvenile

steelhead each in the lower portion of Scott Creek which usually comprises a lagoon, although

no lagoon was formed on this date because the creek was open to the ocean. The total number of

trout in about 90 m of stream was estimated at 1,500–3,000 fish. The steelhead ranged in length

from about 10 to 25 cm, although most were about 13–18 cm long. The observer believed that

these fish would be migrating back upstream later during the fall and winter, as was seen in

nearby Waddell Creek (L. Shapovalov, CDFG, unpubl. field corr. of 15 October 1942).

During a survey of low flow conditions in coastal streams during July 1952, the

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California State Division of Water Resources reported that juvenile steelhead were present in

lower Scott Creek, about 450 m upstream from Highway 1.

The CDFG made an informal survey of Scott Creek on 23 December 1960 to check for

the presence of adult steelhead. The creek had no freshwater connection with the ocean on that

date, thus blocking entry of migrant spawners. Although no adults were observed in the creek,

juvenile steelhead, 5–7.5 cm in length, were common throughout the survey area.

A more extensive survey of the lowermost 6.4 km of the creek was conducted by the

CDFG on 5 February 1961. High quality spawning grounds were abundant, especially upstream

from Big Creek. Rearing habitat in the form of pools and cover was abundant in the upper 4.8

km of the survey area. No migration barriers were noted in the survey area, although the 6 m

waterfall in the headwaters was mentioned as still being a barrier. The numerous pump

diversions for irrigation continued to desiccate portions of the lower stream. On this date,

however, the creek was open to the ocean. The Scott Creek headwaters and tributaries had

perennial flow. One adult steelhead was observed about 90 m above the confluence with Mill

Creek. Juvenile steelhead, 5–10 cm in length, were common throughout the survey area, and

occurred at visually estimated densities of about 100–150 trout/km and 150–300 trout/km, above

and below Big Creek, respectively. Natural propagation appeared to be highly successful.

Angling pressure for adult steelhead was thought to be heavy.

CDFG file documents from 1961–64 reiterated the annual problems associated with

unscreened diversion of irrigation water from lower Scott Creek, and resultant losses of large

numbers of juvenile steelhead and coho salmon from entrainment and desiccation.

Instream conditions at Scott Creek had apparently degraded appreciably by the time of

the next CDFG survey on 14–16 June 1982 (L. Turner, CDFG, unpubl. memo. of 25 June 1982).

The stream was surveyed from the mouth to about 10.5 km upstream from the Pacific Ocean in

the headwaters. Siltation had apparently become a problem in the stream, perhaps as a result of

the heavy storms of January 1982. Spawning gravels were shallow and occurred only in

scattered patches. Pools were shallow and silted in, and logjams provided the only cover in most

of the survey area; there were some deeper pools and undercut banks in the upper stream.

Thirty-five logjams were counted in the survey area, of which 22 were rated as partial and 10 as

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complete barriers to fish migration. Despite the lack of potential spawning sites and numerous

hindrances to fish movement, local residents reported that the stream received its largest run of

adult steelhead and coho salmon since the 1976–77 drought. Furthermore, reproduction was

apparently highly successful because, according to the surveyor, any 30 m section of the creek,

from the mouth to the headwaters, “literally explode(d)” with hundreds of young-of-the-year

salmonids.

On 14 August 1984, the CDFG captured 192 juvenile steelhead in Scott Creek, by

electrofishing seven reaches comprising 195 m of habitat upstream from the bridge crossing on

Big Creek Lumber Company property (trout density ≥ 1 fish/m). The fish averaged 6.4 cm SL

(SD = 2.8 cm; range, 3.0–20.8 cm SL); thus, the sample reflected dominance of 0+ trout in the

age structure of the juvenile population in this portion of the creek. Similarly, age 0+ and 1+

steelhead were abundant in an approximately 180 m reach of Scott Creek, just upstream from the

Mill Creek confluence, during a brief CDFG survey on 10 July 1985.

The long-term problem of water extraction in lower Scott Creek intensified during the

recent six-year (1986-87 to 1991-92) drought in California. During August 1987, most of creek,

from the lagoon to a diversion point about 1.6 km upstream, was dewatered, leaving only

stagnant, isolated pools as fish habitat (L. Ulmer, CDFG, unpubl. memo. of 30 September 1987).

One known downstream-moving adult steelhead and several juveniles were able to survive, at

least temporarily, in these pools, although dead steelhead were also observed in this stream

reach. About 0.5 km above the diversion, the abundance of juvenile steelhead and coho salmon

was estimated at 974 fish/km (SE = 203 fish/km; estimate made by use of electrofishing and

three-pass depletion method), with coho salmon representing 9% of the catch. Thus, the

potential loss of juvenile steelhead in the lower creek was on the order of about 1,400 fish, due to

the effects of water removal and subsequent deterioration of water quality in remaining pools.

Steelhead losses may have also occurred in the lagoon as the water level dropped due to reduced

inflow, and maximum surface water temperature approached 25° C and salinity increased to over

5 ppt (J. J. Smith, San Jose State University, unpubl. data). Similar conditions occurred in the

lagoon again in August 1988 when most steelhead present died. Observed dead steelhead ranged

from 11 to 40 cm FL (mean ± SD = 16 ± 3 cm FL; n = 97), while stressed and dying individuals

96

were generally smaller, 8–14 cm FL (n = 9). Large sculpins were also found dead.

In addition to Jennifer Nelson’s memorandum on downstream migrant trapping results in

1992, population estimation data collected by Snider in 1988 and Jones in 1991 are also

currently being summarized.

Big Creek

Scott Creek’s largest tributary, Big Creek, has played an important role in the culture of

steelhead in Santa Cruz County. The Big Creek Hatchery began operations in 1927 as a

supplement to the Brookdale Hatchery on the San Lorenzo River, because of a deficient water

supply at the latter site (D. Streig, Monterey Bay Salmon and Trout Project, unpubl. report:

History of fish cultural activities in Santa Cruz County with reference to Scott and Waddell

creeks). As at Brookdale, eggs from Scott Creek steelhead were hatched at the new facility, and

the young reared for local stocking. The Big Creek Hatchery was not without its own problems,

however, where breakouts of furunculosis greatly reduced production in 1928 and 1939. Heavy

flooding in early 1940 severely damaged the hatchery (Leitritz 1970), as well as the Scott Creek

Egg Collecting Station, and operations at both facilities were discontinued. Consult Dayes

(1987) for further information pertaining to the history of the Big Creek Hatchery.

CDFG fish stocking records from the 1930’s showed that the Big Creek steelhead

population was supplemented with 26,000 juveniles in 1930 (10,000 above and 16,000 below an

impassable waterfall, respectively); 27,000 in 1932 (12,000 above and 15,000 below the

waterfall, respectively); 7,220 in 1933; 14,768 in 1934; 60,000 in 1935; 30,000 in 1936; 136,956

(@ 268–1,340/kg) from Big Creek Hatchery in 1938; and 183,971 (@ 38–4,233/kg) from Big

Creek Hatchery in 1939.

Historically, Big Creek has supported a small run of wild steelhead. The creek was

surveyed by the CDFG in 1934. Anadromous salmonids had access to only the lowermost 4 km

of the creek because of an impassable waterfall barrier, leaving about 7 km upstream. Juvenile

steelhead and coho salmon were present in the stream portion below the waterfall. Salmonid

spawning grounds, and consequently the extent of natural propagation, were described as poor.

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The surveyor believed that no wild population of rainbow trout existed above the waterfall, and

that the trout present above the fall were only the result of stocking and not natural propagation.

An hydroelectric power generating plant was located in the upper watershed which temporarily

diverted water from the creek; its intake was unscreened. Fishing pressure on Big Creek was

rated as heavy.

The CDFG surveyed the lowermost 4 km of the creek up to the waterfall barrier, and the

uppermost 1.6 km of the headwaters, on 13–14 January 1958. The intervening 4.8 km were not

surveyed because of limited access to this stream reach. Much of the stream substrate was

granitic sand. There were some salmonid spawning areas in the lower section but none in the

upper section. Rearing habitat in the form of pools and cover was adequate for juvenile

steelhead in the lower section. In addition to the abovementioned waterfall barrier, two more

such natural barriers reportedly existed in the unsurveyed portion of the stream. One small

summer diversion occurred in the extreme headwaters. No steelhead or coho salmon were

observed during this survey, although local residents reported that these fishes continued to

utilize the lower creek available to them. Contrary to the 1934 survey, a wild population of

resident rainbow trout reportedly inhabited the stream above the waterfall.

The CDFG observed juvenile steelhead in lower Big Creek, at the confluence with Scott

Creek, on 13 October 1959.

When the CDFG surveyed the lower creek up to the first waterfall on 7 July 1960,

spawning and rearing conditions for steelhead were apparently much the same as in the 1958

survey. The visually estimated density of young-of-the-year steelhead was 3–4 fish/30 m

throughout the survey area. These fish were 4–5 cm in length. Siltation was noted as a factor

which was possibly limiting steelhead production in the creek. The local land owners claimed

that the adult steelhead run had declined considerably since 1930.

During a brief check of a 400 m reach of lower Big Creek on 5 February 1961, the CDFG

saw no adult spawners, but juvenile steelhead were observed at a visually estimated density of 1–

3 fish/pool.

The overall condition of lower Big Creek as a salmonid production area apparently

improved during the ensuing 20 years. When surveyed for logjam barriers by the CDFG on 17

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June 1982 (L. Turner, CDFG, unpubl. memo. of 29 June 1982), spawning areas for steelhead

were described as being adequate and existed from the mouth to the first waterfall, the upstream

limit of the survey. Pools and cover were generally adequate for juvenile steelhead, although

low-velocity areas for newly-emerged fry were scarce. Young-of-the-year salmonids were

common in lateral habitats. Siltation was noted as minor, and none of the six logjams in the

survey area comprised a complete barrier to fish migration.

The CDFG observed an abundance of young-of-the-year steelhead in lower Big Creek on

9 July 1985. A screened agricultural diversion existed on the creek, about 18 m upstream from

the Swanton Road bridge crossing.

During habitat mapping surveys conducted by the CDFG during July–September 1987,

juvenile steelhead were observed at several locations in Big Creek, from the confluence with

Scott Creek to near the confluence with Berry Creek. Maximum estimated trout lengths ranged

from 15 to 25 cm in some pools. Sediment sources were identified; e.g. eroding stream banks

and road crossings.

Dean Marston’s 1992 report is currently being reviewed for inclusion here.

In 1982, fish culture activities on Big Creek were resurrected at the old CDFG hatchery

site by the Monterey Bay Salmon and Trout Project. A summary of these operations is currently

being prepared.

Little Creek

Jennifer Nelson’s 1992 survey report for Little Creek is currently being reviewed for

inclusion here.

Mill Creek

Mill Creek is the uppermost of the larger tributaries to Scott Creek. Steelhead and coho

salmon have historically had access to the lowermost 4.2 km of the creek, at which point a series

of natural waterfalls blocks upstream migration of fishes. There is a reservoir in the headwaters

of the creek, the dam of which was constructed in 1889. The dam, which diverted water for

power production, lacked a fishway. The report of a 1934 CDFG survey indicated that spawning

grounds existed in the lower creek which were utilized by steelhead and salmon. Fishing

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pressure was rated as heavy. Stream flow was apparently very low during late summer. Early

records showed that the CDFG supplemented the Mill Creek steelhead population with 8,000

juveniles in 1932.

In a CDFG survey made of Mill Creek Reservoir on 29 July 1948, it was reported that

“considerable numbers” of rainbow trout inhabited the reservoir, and that natural reproduction

was highly successful in the high quality spawning grounds which existed in Mill Creek above

the impoundment. The reservoir had apparently been stocked with rainbow trout at irregular

intervals since at least the early 1920’s. It was not mentioned if wild resident rainbow trout were

historically also present in the drainage above the waterfalls.

The CDFG surveyed the lowermost 2.4 km of Mill Creek on 25 July 1957. High quality

spawning grounds still existed in the lower creek, and rearing habitat for juvenile steelhead in

the form of pools and cover was at least adequate. Young steelhead, averaging 5–7.5 cm in

length, were very abundant, and natural reproduction was considered highly successful. Angling

pressure was light. In addition to the abovementioned waterfalls and dam, a logjam created a

potential migration barrier at the creek mouth. The main diversion on the creek was at Mill

Creek Reservoir, although one small residential diversion was also noted in the lower stream.

The Mill Creek Dam had washed out the previous winter, and the earthen dam material, as well

as soft sediment from the reservoir bottom, covered the stream substrate for about 1.6 km below

the dam. However, this condition did not persist into the downstream steelhead production area

on the survey date.

The CDFG observed an abundance of juvenile steelhead in Mill Creek, at its confluence

with Scott Creek, on 13 October 1959.

The lowermost 4.2 km of Mill Creek, up to the first waterfall barrier, were surveyed by

the CDFG on 7 July 1960. Spawning and rearing conditions for steelhead were apparently

unchanged from the 1957 survey. Visually estimated densities of juvenile steelhead were high

and generally increased as one progressed downstream through the survey area. The estimates

ranged from 30 trout/30 m near the waterfalls, to 100 trout/30 m near the creek mouth. The trout

were about 2.5–12.5 cm in length, and averaged 5–7.5 cm. So, the juvenile population

apparently comprised age 0+ and 1+ trout, with 0+ trout probably dominating in number. Mill

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Creek was rated as an exceptional steelhead stream for its size, although it was the surveyor’s

opinion that any increase in upstream water diversion would significantly impact steelhead

production.

The CDFG checked an approximate 1.6 km reach of lower Mill Creek on 5 February

1961. No adult steelhead were seen, but juveniles were abundant and occurred at densities of 5–

10 trout/pool.

Soquel Creek Drainage Soquel Creek is historically one of the most important steelhead spawning and rearing

streams in Santa Cruz County. Snyder (1913) found juvenile steelhead/rainbow trout in Soquel

Creek when he sampled there in summer 1909. The steelhead population was supplemented

with a total of 30,800 juveniles (@ 1,060–1,130/kg) from Brookdale Hatchery during June–July

1938. A local angler reported that an estimated 5,000–6,000 juvenile steelhead (mostly <18 cm

long) were taken on hook-and-line from Soquel Creek lagoon during May 1947.

Soquel Creek, below the confluence of the east and west branches, was surveyed by the

CDFG on 8 October 1959. Spawning and rearing habitats for steelhead were adequate, and there

were no migration barriers. Juvenile steelhead were observed at every survey station. These fish

ranged in length from 2.5 to 25 cm, and averaged about 5 cm. Juvenile abundance in mainstem

pools was generally not as great as in pools in the east and west branches (see below). At the

time of this survey, Soquel Creek was stocked with catchable rainbow trout during the summer

trout season each year.

Based on data collected during the 1959 surveys in the main stem and east and west

branches of Soquel Creek, the abundance of juvenile steelhead in the system was estimated at

17,500 fish. CDFG population surveys during the summer of 1962 indicated a similar number of

young steelhead. This juvenile abundance corresponded to an adult steelhead run of

approximately 500–1,000 spawning pairs (W. A. Evans, CDFG, unpubl. memo. of 5 November

1962).

The CDFG made two streamflow surveys in Soquel Creek during the summer of 1965,

during which fish measurements were made. At a single station on 24 June 1965, juvenile

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steelhead averaged 9.1 cm in length (range, 6.9–13.0 cm) at a visually estimated density of about

330–460 trout/100 m. On 19 August 1965, juveniles at one site averaged 6.9 cm in length

(range, 5.6–7.9 cm) at a visually estimated density of about 330–490 trout/100 m.

A CDFG document from early 1973 summarized a variety of statistics regarding the

Soquel Creek steelhead stock and fishery up to that time (E. C. Fullerton, CDFG, unpubl. memo.

of 5 January 1973). In addition to the estimate of adult run size mentioned above, the winter

fishery for steelhead and coho salmon comprised about 1,000 angler-use days in 1970. The

summer trout fishery, which targeted juvenile steelhead rearing in the stream, comprised about

12,000 angler-use days in 1970. Steelhead used about 32 km of the Soquel Creek system for

spawning and rearing. Resident rainbow trout existed in about 26 km of stream above barriers to

migratory salmonids.

In late fall 1981, the mean ± SD density of smolt-sized steelhead at four main stem sites

was 1.0 ± 0.7 trout/m, which was well below the county-wide average (derived from Smith

1982b). The mean ± SD of the site-specific mean lengths of these fish was 94 ± 7 mm SL,

which was slightly below average.

Young steelhead were observed during a water quality investigation of Soquel Creek

lagoon in May 1988 (CDFG, unpubl. file report of 21 May 1988). Juvenile steelhead were

observed feeding beneath the bridge in the lower lagoon. In the upper lagoon, juveniles were 4–

6 cm long at a density of 30–40 trout/100 m. Some 30–40 juvenile steelhead were observed at

the inflow to the lagoon.

STATUS: The Soquel Creek steelhead stock declined significantly during the 1970’s,

coincident with increased diversions and drought which reduced stream flow. Siltation and other

pollution, as well as the presence of migration barriers, have likely also contributed to this

decline.

Bates Creek

Bates Creek, a lower Soquel Creek tributary, was surveyed by the CDFG in March 1957,

and was rated as a poor spawning and rearing stream for steelhead. The watershed was logged

and, in addition to debris in the stream, erosion had led to extensive siltation. Spawning

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substrate was generally lacking throughout the survey area. Juvenile steelhead, about 7.5 cm in

length, occurred only in low densities, and spawning success was rated as low. There was a dam

lacking a fishway about 2.4 km above the mouth. No fish were seen during brief CDFG surveys

in December 1960 and January 1962.

However, steelhead have continued to use this stream. For example, in late fall 1981, the

density of smolt-sized steelhead at one site in Bates Creek was 2.0 trout/m, which was about half

the county-wide average (derived from Smith 1982b). The mean length of these fish was 91

mm SL, which was also below average. In July–August 1986, juvenile steelhead were observed

in numerous pools downstream from the dam, and resident rainbow trout above the dam (County

of Santa Cruz 1986).

East Branch Soquel Creek

The CDFG surveyed 11 km of the East Branch Soquel Creek on 28 September 1959,

beginning at the confluence with the west branch. Spawning and rearing habitats were in

excellent condition. There were natural boulder and bedrock barriers in the upper stream.

Young trout observed above the barriers may have been resident rainbow trout. The east branch

was rated as the most productive steelhead area in the Soquel drainage system; 11,500 juvenile

steelhead were counted along the length of stream available to migratory trout. These fish

averaged about 5 cm in length (range, 2.5–15 cm). At the time of the survey, the lower section

of the east branch was stocked annually with catchable rainbow trout.

In late fall 1981, the mean ± SD density of smolt-sized steelhead at three sites in the east

branch was 2.0 ± 2.0 trout/m, which was below the county-wide average (derived from Smith

1982b). The mean ± SD of the site-specific mean lengths of these fish, 102 ± 14 mm SL, was

above average. In July–August 1986, juvenile steelhead were abundant in the east branch, from

its confluence with the west branch to a bedrock waterfall nearly 10 km upstream (County of

Santa Cruz 1986). Resident rainbow trout populated high quality salmonid habitat above the

falls.

The east branch tributary, Amaya Creek, was surveyed by the CDFG in March 1957. It

was noted as a mostly pristine spawning and nursery stream for Soquel Creek steelhead. The

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stream had good to very good spawning areas and adequate rearing habitat. There were no

diversions and only partial barriers formed by logjams. Juvenile steelhead, averaging about 7.5

cm in length, were common throughout the 1.6 km survey area. A local resident reported that

adult steelhead had historically migrated nearly up to Stetson-Longridge Roads to spawn.

By the time Amaya Creek was surveyed again in October 1959, the effects of logging

had significantly degraded the stream habitat quality for producing steelhead. Spawning areas

were now practically nonexistent in the upper two-thirds of the stream, siltation as a result of

erosion was common, and the large amount of logging debris clogging the stream created many

migration barriers. About 1,500 young-of-the-year steelhead were observed, but only in the

lowermost third of the stream.

Amaya Creek was not surveyed again by the CDFG until May 1982, following the heavy

storms of January 1982. Only the lowermost 0.4 km of the stream was accessible due to fallen

trees and logjams, and a few steelhead fry were seen only at the creek mouth. The stream

apparently no longer supported a run of steelhead. In July–August 1986, O. mykiss were

observed in the creek; these fish were believed to be resident rainbow trout due to the presence

of major logjam barriers (County of Santa Cruz 1986).

The east branch tributary, Hinkley Creek, was surveyed by the CDFG in 1959 and 1977

(Smith 1982b), although the file containing these survey reports was not located. In late fall

1981, the density of smolt-sized steelhead at one site in Hinkley was 1.0 trout/m, which was well

below average (derived from Smith 1982b). The mean length of these fish was 84 mm SL,

which was also well below average.

Moore’s Gulch

In late fall 1981, the density of smolt-sized steelhead at one site in Moore’s Gulch, a

main stem Soquel tributary, was 1.6 trout/m, which was well below average (derived from

Smith 1982b). The mean length of these fish was 97 mm SL, which was near average.

West Branch Soquel Creek

The CDFG surveyed the West Branch Soquel Creek on 30 August 1946, in its middle

portion at the “Napier” dam located downstream from Laurel Creek. This dam was a complete

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barrier to migrant spawners. Young-of-the-year steelhead were abundant below the dam.

Spawning areas were also observed above the dam, and juvenile resident rainbows, 5–9 cm long,

were fairly common up to the confluence with Laurel Creek.

The headwaters of the west branch, upstream from Laurel, were surveyed by the CDFG

on 25 August 1948. Siltation and rock- and logjams were noted as problems, the jams being the

result of abandoned railroad and logging operations. Juvenile resident rainbow trout, 5–13 cm

long, were scarce.

The west branch was fully surveyed by the CDFG on 5 October 1959. Spawning areas

were abundant, and rearing habitat was adequate. Juvenile steelhead were present, apparently in

low densities.

In late fall 1981, the mean ± SD density of smolt-sized steelhead at three sites in the

west branch was 3.7 ± 2.2 trout/m, which was about average (derived from Smith 1982b). The

mean ± SD of the site-specific mean lengths of these fish, 87 ± 5 mm SL, was well below

average. In July–August 1986, high densities of young-of-the-year steelhead were observed in

the west branch, from its confluence with the east branch to the water supply dam near the

confluence of Burns and Laurel creeks (County of Santa Cruz 1986). O. mykiss were seen in

lower densities above the dam; these fish may have been resident rainbow trout.

In late fall 1981, the mean ± SD density of smolt-sized steelhead at two sites in Hester

Creek, a west branch tributary, was 2.3 ± 0 trout/m, which was rather below average (derived

from Smith 1982). The mean ± SD of the site-specific mean lengths of these fish was 88 ± 2

mm SL, and thus also below average. In July–August 1986, juvenile steelhead were abundant in

the lowermost 1.3 km of Hester Creek. Fish believed to be resident rainbow trout inhabited the

stream in relatively low densities above a bedrock waterfall.

Waddell Creek Drainage Waddell Creek and its steelhead population are best known as the objects of study by

Shapovalov and Taft (1954). This landmark study provided data on the natural variation in

numbers of migrant spawners, as produced by the stream system during the 1930’s3. During the

3. A summary and analysis of the life history of Waddell Creek steelhead, based on data from Shapovalov and Taft

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nine-year study period (1933–34 through 1941–42), estimated total run size ranged from 428 to

554 and averaged 481 (SD = 40; data from Table 35 in Shapovalov and Taft 1954). The overall

decreasing trend in total run size (Fig. 13) was nearly significantly correlated with time (r 2 =

0.42, p = 0.06), although it is not known if this represented an actual decline in the population, or

a temporary trend of suboptimal recruitment years, possibly as a function of the negative

density-dependent stock-recruitment relationship of the population (see Life History Analysis).

Based on a CDFG file document (CDFG, unpubl. field note of 11 February 1962), a large

run of adult steelhead reportedly entered Waddell Creek during the first week of February 1962.

Yet another file document indicated that, as of 1967, local CDFG wardens estimated the adult

steelhead run in Waddell Creek at 350 fish or more (M. L. Johnson, CDFG, unpubl. field corr. of

April 1967).

(1954), were presented earlier in the Results under Life History Analysis, and will not be repeated here.

Seining surveys were conducted in lower Waddell Creek, downstream from the Highway

1 bridge, on 11 November 1970 and 1 May 1971 (surveyors and their affiliation not identified).

Juvenile steelhead were present throughout the survey area in both surveys, and in the November

1970 survey, all were <25 cm in length and appeared to be age 1+ fish.

SilverKing Oceanic Farms (originally Pacific Marine Enterprises) operated a commercial

“salmon ranching” operation in the Waddell Creek lagoon during the late 1960’s and early

1970’s. Steelhead, coho salmon, and chinook salmon from exotic hatchery stocks were reared at

their private hatchery on Bean Creek, marked, and then released at Waddell Creek to emigrate

and grow to maturity in the Pacific Ocean. The mature fish would then return to be captured at a

weir situated in lower Waddell Creek. A total of 77,000 steelhead yearlings was released at

Waddell Creek through 1971, representing progeny from the 1967-68 through 1970-71 brood

years (M. L. Johnson, CDFG, unpubl. progress report of 7 January 1972). Although the data

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were incomplete, adult returns during the 1970-71 season included 16 marked steelhead,

comprising nine females and seven males. Among these fish, two females weighed about 5 and

7 kg each, two males were also full-size adults, and five males were “jacks” (males 25–35 cm in

length which have spent only one summer rearing in the ocean). In addition, 272 wild steelhead

were passed upstream at the trapping facility. As of 7 January 1972 (1971-72 season), 17 wild

steelhead had been counted at the trap. The entire operation was discontinued after a flood in

February 1973 destroyed the trapping facility.

Five adult steelhead, observed in a creel census conducted by Cabrillo College biology

students during the 1971-72 season (unpubl. data in CDFG file), ranged in length from 53 to 75

cm. Capture dates for these fish extended from 26 December 1971 through 6 February 1972.

Juvenile steelhead were incidentally captured while seining for striped bass (Morone

saxatilis) in the Waddell Creek lagoon on 14 March 1972 (K. Boettcher, unpubl. file letter of 16

March 1972 to M. Johnson, CDFG).

The main stem and east fork of Waddell Creek were surveyed by the CDFG during 4–7

& 18 August 1980, from the mouth to 12 km upstream (B. Jong, CDFG, unpubl. file report of

September 1980). Siltation, from extensive streambank erosion, was occurring in especially the

lowermost 2 km of the main stem. Suitable spawning and rearing habitats for steelhead were

observed, presumably further upstream. Juvenile steelhead densities at two 30 m mainstem sites

were 29 (95% C.I., 4–150) and 4 (0–180) trout/m2, as determined by electrofishing and

application of the removal method of population estimation. Steelhead at one site in the lower

east fork occurred at an estimated density of 14 (5–60) trout/m2. Beginning at about 0.8 km

upstream from the confluence with the west fork, a series of falls marked the upstream limit for

movement of anadromous fishes in the east fork. Densities of resident rainbow trout at three 30

m sites in the east fork were 33 (5–90), 3 (0–90), and 12 (0–120) trout/m2. Spawning and

rearing habitats were reportedly limited in this high gradient stream area, yet densities of resident

trout were comparable to those of juvenile steelhead. Sewage plant effluent from the Big Basin

Redwoods State Park was identified as a potential pollution source of eutrophicating nutrients

and toxic chlorine. Of five logjams located in the main stem, only one was a partial migration

barrier. About 13% of the Waddell Creek watershed was logged between 1860 and 1966.

107

On 14 August 1984, the CDFG captured 93 juvenile steelhead by electrofishing in the

main stem Waddell Creek immediately downstream from the forks, and upstream in both the east

and west forks. The fish averaged 6.6 cm SL (SD = 2.0 cm; range, 3.3–13.7 cm SL); thus, the

sample reflected dominance of 0+ trout in the age structure of the juvenile population in this

portion of the creek system.

The negative effects of water extraction on California streams intensified during the

recent six-year (1986-87 to 1991-92) drought. During August 1987, most of lower Waddell

Creek, from the lagoon to an agricultural diversion dam about 1.4 km upstream, was dewatered

(L. Ulmer, CDFG, unpubl. memo. of 30 September 1987). About 90 m above the diversion dam,

the abundance of juvenile steelhead and coho salmon was estimated at 315 fish/km (estimate

made by use of electrofishing and three-pass depletion method), with coho salmon representing

10% of the catch. Only 18 juvenile steelhead and coho salmon were collected in about 0.6 km of

stream below the diversion. Thus, the potential loss of juvenile steelhead in the lower creek was

on the order of about 400 fish, due to the effects of water removal and subsequent deterioration

of water quality in remaining pools. Steelhead losses may have also occurred in the lagoon as

the water level dropped because of reduced inflow, leading to unsuitable water quality conditions

for juvenile steelhead. Similar conditions apparently occurred in the lower stream and lagoon

again during the summer of 1988.

With regard to the latter point, Smith (1987, 1990) determined the importance of the

Waddell Creek lagoon as rearing habitat for juvenile steelhead prior to their migration to the

ocean.

The spring downstream migration of juvenile and post-spawner steelhead has been

monitored by trapping since 1990, and this operation has produced at least preliminary results

regarding the size and composition of this migration (J. J. Smith, San Jose State University, pers.

comm.). In addition, an attempt was made to trap the upstream spawning migration during the

1992-93 season, although high flow conditions hampered this effort.

There are several small headwater tributaries to Waddell Creek for which there is no

documentation of presence or absence of O. mykiss. These streamlets include the west branch

tributaries, Timms and Kelly creeks; and the east branch tributaries, Blooms Creek (including its

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tributary, Sempervirens Creek along with Union Creek) and Opal Creek (including its tributaries,

Rogers and Maddock creeks). These small feeder creeks are nonetheless important because they

contribute to the perennial flow in the upper Waddell Creek drainage.

Wilder Creek Drainage

MONTEREY COUNTY

Alder Creek Drainage When surveyed by the CDFG on 19 July 1961, steelhead apparently entered the lower reaches of

Alder Creek during wet years. The stream had a relatively high gradient, and spawning areas

were scarce and limited to pockets of fine gravel scattered throughout the upper and lower

sections of the 3.2 km survey area. Rearing habitat for juvenile steelhead, in the form of pools

and cover, was adequate. The middle section contained three complete barrier waterfalls. No

permanent diversions were observed. The stream apparently contained both resident rainbow

trout and juvenile steelhead throughout the survey area. Fish lengths were 2.5–15 cm, with the

modal length at about 9 cm SL. In a series of 20 pools, the average trout density was 1.75

fish/pool. Shallow pools in the upper reaches of the creek contained few, if any, trout. Due to

the barriers, it was recommended that the stream be managed for brown trout.

On 8 May 1962, 6,000 brown trout fingerlings were stocked in the creek. Survival was

apparently low as no brown trout were captured by hook-and-line or hand braille when the creek

was sampled during 1–2 September 1963 (M. L. Johnson, CDFG, unpubl. memo. of 14 October

1963). However, juvenile steelhead/rainbow trout were caught, ranging in length from 5 to 15

cm.

The overall condition of Alder Creek was apparently unchanged when the lowermost 1.2

km were surveyed by the U.S. Forest Service (USFS) on 17 September 1981. Small to moderate

numbers of steelhead reportedly ran up the stream. The average estimated density of trout was

10–12 fish/30 m. Fish lengths ranged from 2.5 to 15 cm, and averaged about 7.5 cm.

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Anderson Canyon Creek Drainage Anderson Canyon Creek, a small steep-gradient perennial stream, has evidently not been

populated by steelhead within recent geological history, owing to a 3.7 m waterfall near the

creek mouth at the Pacific Ocean. Resident rainbow trout have reportedly been caught in the

creek in the past, but none has been observed in recent years, including during an electrofishing

survey just west of Highway 1 on 5 April 1989 (Rischbieter 1990c). The Rat Creek wildfire in

1985 and subsequent heavy storms during the winter of 1985-86 may have extirpated the trout,

or nearly so. As of 1989, the drainage had apparently recovered from these perturbations, which

would allow for the re-expansion or reintroduction of the species.

Big Creek Drainage The Big Creek drainage is among the largest in southern Monterey County utilized by

steelhead. Shapovalov (1946) wrote that, “Good runs of steelhead ascend the stream from the

sea and spawn in both forks below the falls. Resident fish of the steelhead-rainbow complex and

possibly some survivors and descendants of stocked trout are present both above and below the

falls in each fork.”

The lowermost 2.4 km of Big Creek were surveyed by the CDFG on 6 September 1961.

Suitable spawning gravels were scarce in the upper portion of the survey area, but more

abundant below the confluence with the Big Creek tributary, Devil’s Canyon Creek, which is

located about 1.1 km upstream from the mouth. Rearing habitat, in the form of pools and cover,

was adequate. A bedrock waterfall barrier, about 2.4 km upstream from the mouth, marked the

upstream limit for steelhead migration. No diversions were seen. At the confluence of Big

Creek and Devil’s Canyon Creek, 5–10 cm long juvenile steelhead/rainbow trout occurred at a

visually-estimated density of 8 fish/30 m. Trout densities were lower above this point, but as

high as 55 fish/30 m near the creek mouth. Trout in the lower stream were up to 15 cm long.

Although none was seen, brown trout also reportedly occurred in the creek system, including

Devil’s Canyon Creek.

Since 1978, a significant portion of the Big Creek drainage has been in the possession of

the University of California and administered as an ecological preserve and scientific research

110

area. According to personnel at the reserve, both the frequency of large adult steelhead spawners

(>50 cm TL) and the size of the runs appeared to decrease overall during the 1986/87–1991/92

drought (J. Smiley, Landels-Hill Big Creek Reserve, pers. comm. of 13 December 1993). For

example, two runs of 10 or so readily-noticeable adults were seen during the 1986-87 spawning

season. Nothing comparable has been observed since then. During the relatively wet 1992-93

spawning season, only smaller adults (about 35–45 cm TL) and their redds were seen. Juvenile

steelhead/rainbow trout have persisted in the creek system; these fish are mostly <18 cm TL

although an occasional 25–30 cm long individual is observed. Overall, the Big Creek drainage is

a stable stream system that should continue to provide suitable spawning and rearing habitat for

both steelhead and rainbow trout.

Devil’s Canyon Creek

Devil’s Canyon Creek (a.k.a. South Fork Big Creek) was surveyed by the CDFG on 24

July 1945, from the confluence with Big Creek to an impassable waterfall barrier about 2.8 km

upstream, near the confluence with the North Fork Devil’s Canyon Creek. Juvenile

steelhead/rainbow trout, including young-of-the-year, were common up to the falls.

The entire creek (13 km) was surveyed by the CDFG during 29–30 August 1961.

Spawning gravels were scarce in the upper survey area, and were largely cemented by limestone

in the lower stream. Rearing habitat, in the form of pools and cover, was adequate for juvenile

steelhead/rainbow trout. Bedrock falls were numerous. Juvenile steelhead/rainbow trout were

seen throughout the stream, including 6–8 cm long young-of-the-year above the confluence with

Big Creek. In the headwaters above the steelhead zone, resident rainbow trout, ranging in length

from 2.5 to 18 cm and probably comprising at least three age-classes, were sampled by use of

cresote. Based on very limited sampling, approximate densities were 10+ trout/30 m near Big

Creek, and 30+ trout/30 m in the headwaters. Most fish were young-of-the-year.

Devil’s Canyon Creek, from the confluence with the north fork to the middle and south

fork headwaters, was surveyed by the U.S. Forest Service during 4–5 October 1981. The

stability of the watershed was reduced by the Gamboa fires, although the stream itself was

generally in good condition. Natural bedrock falls, 3 –18 m high, were common throughout the

survey area and continued to preclude steelhead access beyond the north fork confluence, as

111

described above. An abundance of deep pools continued to provide high quality rearing habitat

for rainbow trout. Resident rainbow trout, about 2.5–23.0 cm long, were common in abundance,

and occurred in average estimated densities of 82 and 49 trout/100 m in the main stem/south fork

and middle fork, respectively.

Big Sur River Drainage The Big Sur River drainage is currently among the largest (about 120 km2) of those

systems south of San Francisco Bay that remains mostly pristine. Within recent geological

history, only the lowermost 12 km or so of the river have been accessible to steelhead. Upstream

migration beyond this point in the steep and rugged gorge section of the river has been blocked

by a natural bedrock fall. This feature marks the boundary above which the river flows through

the Ventana Wilderness within the Los Padres National Forest. Pfeiffer Big Sur State Park is

situated immediately downstream from this point along a portion of the lower river where

redwoods are a major component of the riparian zone. This far south along the California coast,

fog no longer maintains the moisture climate necessary for continuous stands of redwoods, and

the steep hillsides that comprise the Big Sur drainage are otherwise dominated by grassland,

chaparral, and oak woodland. The lowermost 6.4 km of the river flow through Andrew Molera

State Park.

The following is a chronological rundown of available information on Big Sur River

steelhead and resident rainbow trout. The catches of 48 anglers were checked on 1 May 1932,

the opening day of the summer trout season (J. H. Wales, CDFG, unpubl. file report). A total of

451 juvenile steelhead/rainbow trout was observed, about 97% of which were age 1+ and 2+ and

10.0–15.0 cm long. The remainder of the observed catch was trout 18.0–25.0 cm in length and

≥age 2+. Three trout about 30.5 cm in length were reportedly caught, as were three adult

steelhead. Recently-emerged steelhead fry were abundant along the stream margins. Wales

indicated that juvenile steelhead/rainbow trout were planted in the Big Sur River, but did not

know when or how old the fish were at planting.

On 9 April 1940, six adult steelhead were seen in the large pool immediately below the

barrier falls, and many more were reportedly seen there a few weeks earlier attempting to ascend

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the falls (Shapovalov 1940). On 27 March 1946, the CDFG observed a fresh run of adult

steelhead in the river, again as far upstream as the barrier falls. Recently emerged steelhead fry

were also seen downstream from the falls. In 1953, the CDFG began stocking catchable rainbow

trout annually during May–September to support a lower river sport fishery. Prior to that time,

rainbow trout fingerlings had been planted for several years. The stocking area was a 5 km

reach, mostly within Pfeiffer Big Sur State Park. Resident rainbow trout have not been planted

in the Big Sur River since 1975, following adoption of the steelhead rainbow trout policy which

prohibits the planting of resident fish in steelhead drainages.

About 19 km of the Big Sur River, from the bottom of the gorge upstream to Sykes Camp

in the Ventana Wilderness, were surveyed by the CDFG during July–August 1957. Most of the

survey area was upstream from the impassable steelhead barrier, and thus represented the stream

portion inhabited primarily by wild resident rainbow trout. The river canyon was narrow and

steep-sided, and contained many migration barriers. High quality spawning areas were limited.

Rearing habitat was adequate for both juvenile and adult rainbow trout. Rainbow trout, 7.5–25

cm long, were observed throughout the survey area. However, recruitment to the 1957 year-

class was regarded as poor since few young-of-the-year (fish ≤ 5 cm long) were seen.

On 4 January 1961, stream flow just above the lagoon was about 0.6 m3/s, and few adult

steelhead had been reported in the river. Two steelhead, about 0.9 and 4.5 kg, were caught in the

surf outside the lagoon. Other steelhead were also seen outside the river mouth. A 1.4 kg

steelhead was captured on 31 January 1961.

Fisher (1961) captured 338 juvenile steelhead/rainbow trout in a downstream-migrant

trap in the lower Big Sur River, during 30 April–2 June 1959. The number of downstream

migrants captured per day was greatest during the first 3 days of the trapping period, and then

decreased sharply and fluctuated around a much lower level through the remainder of the period.

Most (87%) movement occurred during the night or early morning. Most downstream migrants

were believed to be 1-year-olds. Some 0+ steelhead apparently also entered the trap, although

their relative abundance was probably underestimated due to a low trapping efficiency for fish

that size. Stream flow in the lower Big Sur River averaged 0.7 m3/s during the study period,

which was uncharacteristically low for the month of May. Thus, these steelhead emigration data

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may not be representative for normal or wet water years.

On 19 April 1961, young-of-the-year steelhead/rainbow trout were seen throughout the

stream reach within Pfeiffer Big Sur State Park, and 12.5–15 cm long juveniles were common.

An adult steelhead was caught in the lower river on 31 January 1962. On 28 April 1962,

juvenile steelhead captured on hook-and-line in the lower river at a rate of 1.08 trout/angler hour

ranged in fork length from 10 to 18 cm, and averaged about 14 cm (R. N. Hinton, CDFG,

intraoffice corr. of 31 May 1962). On 15 May 1962, four steelhead estimated at 61 cm and 1.8–

2.7 kg, and one at about 36 cm, were seen in a pool in the lower river area. On 22 May 1962,

juvenile steelhead, 5–10 cm long, were common in abundance in pools up to the base of the

barrier falls. In 1965, the CDFG estimated the annual steelhead spawning run in the Big Sur

River at about 300 fish, based on the observations of local field personnel (California

Department of Fish and Game 1965).

The CDFG surveyed the north and south forks of the Big Sur River in August 1978,

following the Marble Cone fire of 1977 (P. Chappell, CDFG, unpubl. memo. of 11 June 1979).

These headwaters were somewhat degraded due to the fire, yet resident rainbow trout were

common in abundance, as determined by hook-and-line sampling.

Following several attempts and much discussion over the years regarding removal of the

bedrock barrier in the lower gorge, the Big Sur drainage above the barrier was surveyed by the

CDFG and USFS during 14 July–4 August 1981 to determine the quantity and quality of stream

habitat that would become available to steelhead for spawning and rearing (USFS stream survey

reports, and summary by R. C. Benthin, CDFG, unpubl. memo. of 26 August 1981). High

quality steelhead spawning and rearing habitats were observed throughout the survey area,

including: the entire 21.7 km of the main stem; the lowermost 1.6 km each of the mainstem

tributaries, Ventana and Lion creeks, and the lowermost 160 m of the Ventana Creek tributary,

Doolans Hole Creek; the lowermost 7.2 km of the North Fork Big Sur River; and the lowermost

4.0 km of the South Fork Big Sur River up to an 3.7 m high bedrock migration barrier. So, with

removal of the bedrock barrier in the lower gorge, at least 36 km of habitat would become

accessible to steelhead; an unknown proportion of another 19 km of unsurveyed stream sections

would also become available. The mainstem tributaries, Logwood and Terrace creeks, and the

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North Fork tributary, Cienega Creek, all had an impassable bedrock waterfall at their mouths.

The North Fork tributary, Redwood Creek, was full of debris, apparently as a result of the

Marble Cone fire. Resident rainbow trout, including young-of-the-year, were abundant in all

stream sections surveyed, and occurred in section specific visually-estimated average densities of

40–100 trout/30 m. A subsample of 50 hook-and-line captured rainbow trout averaged about 15

cm FL (overall range, 10.0–35.0 cm FL). The USFS stream survey report indicated that the

CDFG had planted rainbow trout at Barlow Flat in 1948, but none since that time in the stream

area above the gorge.

Beginning in the fall of 1981 and through the fall of 1984, a series of modifications was

carried out on the barrier to enhance steelhead passage. Six adult steelhead were observed by the

CDFG on 18 March 1985 between Barlow Camp and the gorge. Adult steelhead have also been

reportedly seen by anglers in upstream areas in subsequent years (K. R. Anderson, CDFG, pers.

comm. of 9 July 1992).

On 7 November 1988, abundance estimates of juvenile steelhead were made by the

CDFG in two sections of the lower river, each about 46 m long. Fish were sampled by

electrofishing, marked, released, and resampled to make Lincoln-Peterson abundance estimates.

In a section just below the confluence with Post Creek, the calculated abundance was 109

trout/30 m. These fish averaged 84 mm FL (range, 55–247 mm FL). The second section,

located in Andrew Molera State Park, contained an estimated 128 trout/30 m. Average fish

length was 82 mm FL (range, 55–140 mm FL). A sample of juvenile steelhead was also

collected in Molera Park by electrofishing on 17 July 1990 (D. C. Rischbieter, California

Department of Parks and Recreation, unpubl. data); these fish averaged 86 mm SL (SD = 32 mm

SL; range, 50–175 mm SL).

The largest adult steelhead reported from the Big Sur River was an illegal catch that

measured 90 cm and weighed about 7 kg (Rischbieter 1990a). During the 1992-93 season, the

reported angler catch of adult steelhead in the Big Sur included one 79 cm female and several 56

cm fish (M. Fitzsimmons, CDFG, pers. comm. of 13 March 1993).

Recent study of juvenile steelhead habitat use in the lower Big Sur River shows that the

entire area, from the lagoon to the gorge, remains highly functional for steelhead production (R.

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G. Titus, CDFG, unpubl. data of 1992–1995). Preliminary analysis suggests that most juveniles

leave the stream after only one year of rearing, and that there is a relatively small proportion of

mainstem fish that appears to be resident rainbow trout. Most mainstem trout are infested with

encysted metacercaria of the monogenetic trematode, Neascus, a condition commonly referred to

as “black spot disease.”

Resident rainbows are still abundant above the barrier falls in the gorge, and these fish

too have black spot disease (C. Carpanzano, U.S. Forest Service, unpubl. letter of 24 September

1993). Some of these trout may be juvenile steelhead, but it is not clear if adult steelhead are

still able to negotiate the barrier falls.

STATUS: Overall, the Big Sur River continues to support a healthy steelhead population, one

that Nehlsen et al. (1991) classified as a stock of special concern.

Juan Higuera Creek

Juan Higuera Creek is the largest perennial tributary to the lower Big Sur River. The

CDFG surveyed the creek on 8 August 1961. Steelhead spawning areas were lacking as stream

substrate materials were cemented by calcium carbonate precipitates. Rearing habitat in the

form of pools and cover also appeared limited. Several potential barriers to upstream movement

of adult steelhead were identified. Two small pipe diversions removed water from the stream.

No fish were seen during the survey although local residents reported that each small pool in the

stream supported one catchable size (15–20 cm long) juvenile steelhead/rainbow trout. Adult

steelhead reportedly migrated into Juan Higuera Creek during high flow periods in winter (R. L.

Moore, CDFG, unpubl. draft memo. of August 1960).

Another long-time streamside resident and landowner corroborated historical presence of

adult steelhead in Juan Higuera Creek (K. Wright for D. Fee, Big Sur, CA, pers. comm. of 4

February 1994). Steelhead were seen and captured in the creek until 1972, when the combined

effects of an upslope fire and heavy flooding washed out the road crossing near the creek mouth.

A culvert was subsequently installed which then created at least a partial barrier to upstream

migrating adult steelhead.

Recent study of juvenile steelhead habitat use in the lower Big Sur River reveals that

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Juan Higuera Creek is still well-populated with juvenile steelhead/rainbow trout (R. G. Titus,

CDFG, unpubl. data of 1992–95). Preliminary analysis of population structure suggests that

lower Juan Higuera Creek is populated by a mixture of juvenile steelhead and resident rainbow

trout, as evidenced by a relatively high proportion of age 0+ fish. What is not clear is whether

steelhead actually spawn in the creek and their progeny rear there, or if juvenile steelhead

migrate into the creek from the Big Sur River. The population in upper Juan Higuera Creek is

much more sparse in comparison, and clearly characterized by a higher proportion of larger,

older individuals, including mature adults, suggesting a resident rainbow trout population

segment.

Post Creek

Post Creek enters the lower Big Sur River within Pfeiffer Big Sur State Park.

Shapovalov (1940a) described the creek as “an inconsequential stream that is reported to go

completely or nearly dry each summer”, in his consideration of potential hatchery sites in the

park and vicinity. In contrast, Rischbieter (1990d) noted the creek as an historically perennial

stream, and when surveyed by the CDFG in 1980, the creek was identified as an important

spawning and rearing area for steelhead. At that time, only the lowermost 275 m of the creek

were accessible to steelhead because of an impassable logjam. The stream habitat consisted

primarily of small pools and low gradient riffles. The calculated juvenile steelhead abundance

for this area was >1,000 fish, or >365 trout/100 m of stream.

The stream habitat at Post Creek has degraded significantly in recent years (Rischbieter

1990d). In 1986, a landslide occurred about 335 m above the creek mouth which introduced a

large amount of sediment into the lower creek. The sediment filled in pools and covered

spawning gravels. The lower creek went dry during the summer–fall period of the drought years

1988 and 1989. Apparently, drought effects were exacerbated by water withdrawal by the

Ventana Inn and other upstream water users. Rischbieter (1990d) concluded that these

conditions precluded steelhead use of the creek, and no fish were seen during a brief survey of

the lower creek on 18 September 1992 (R. G. Titus, Univ. Calif., Berkeley, unpubl. field notes).

Adult steelhead spawned in lower Post Creek during the wet winter of 1992–93, and

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steelhead fry were seen in the creek, above the upper road crossing in the campground, on 10

June 1993 (R. G. Titus, CDFG, unpubl. memo. of 12 August 1993). On 9 July 1993, a 64 m long

section, from the upper road crossing to the first foot trail crossing upstream, was sampled by

electrofishing. Juvenile steelhead abundance was estimated using the two-pass removal method.

The estimated abundance of age 0+ steelhead was about 35 fish (54 fish/100 m), and that of age

1+ steelhead was 2 fish (3 fish/100 m). Age 0+ fish comprised about 94% of the steelhead catch.

The mean (± SD) length of age 0+ steelhead was 55 ± 12 mm TL (n = 34), and the two age 1+

fish were 101 and 137 mm TL. Age 0+ steelhead also occurred between the upper road crossing

and the creek mouth, but no fish were found in the 50+ m of stream spot-checked immediately

above the foot trail crossing. Several potential migration barriers for adult steelhead still exist in

lower Post Creek, including the support structure for the foot trail crossing mentioned above, and

several logjams that have accumulated large volumes of sediment and gravel. Post Creek has

probably supported more extensive steelhead spawning and rearing, as current poor conditions

for steelhead production appear to be the product of logging effects and water diversion. It is not

known if resident rainbow trout persist in the upper creek area.

Bixby Creek Drainage Bixby Creek is a small, spring-fed perennial stream tributary to the Pacific Ocean. It was

surveyed in its entirety (8 km) by the CDFG during 28 June–17 August 1976. The stream

contained high quality spawning and rearing habitats for steelhead. About 25 logjams and snags

existed in the survey area, but they apparently did not impede upstream migration of adult

steelhead as juveniles were found at each of seven electrofishing stations, from the mouth to the

headwaters. Juvenile steelhead abundance was estimated at six stations using the two-pass

removal method. Mean (± SD) density was 112 ± 42 trout/100 m (range, 52–163 trout/100 m).

The trout ranged in size from <3 cm FL to 30.4 cm FL; thus, potentially several age-classes

were present but no details were given regarding population structure. No records were

discovered regarding steelhead use of the Bixby Creek headwater tributaries, Mill and Turner

creeks, nor its largest tributary, Sierra Creek.

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Carmel River Drainage In 1965, the CDFG estimated the annual steelhead spawning run in the Carmel River at

about 1,650 fish, based on the observations of local field personnel (California Department of

Fish and Game 1965).

The CDFG files and other material on the Carmel River are currently being reviewed as

the basis for this account. Included is the long-term study summarized by Snider (1983); the

assessment report of Dettman and Kelley (1986) and other reports by D. W. Kelley &

Associates; and Kyle Murphy’s 1992 survey report of the Carmel River tributary, San Clemente

Creek. Nehlsen et al. (1991) listed the Carmel River steelhead stock as being at a high risk of

extinction. The decline in this population is the result of blocked access to historic spawning and

rearing areas upstream of dams, and extensive water diversion.

Doud Creek Drainage No juvenile steelhead/rainbow trout were found in lower Doud Creek when spot-sampled

with a dip net on 18 October 1989 (Rischbieter 1990b). Although perennial, this stream may

simply be too small for steelhead use.

Garrapata Creek Drainage Although a known steelhead stream, no early records were discovered regarding the wild

steelhead population in Garrapata Creek. In early 1966, rainbow trout in a privately owned

hatchery on the creek were diagnosed with whirling disease, which is caused by the protozoan,

Myxosoma cerebralis. Evidently, the disease spread into the creek itself as uninfected fish

placed in the creek became infected. Follow up studies were curtailed due to personnel

constraints and it is generally unknown whether the wild steelhead stock was affected by the

disease. However, in connection with permitting of a new trout farm on the creek in 1975, there

was no evidence of whirling disease in test fish held in Garrapata Creek water on the farm

property.

Considerable development occurred in the Garrapata Creek drainage during the 1980’s

for which there was great concern regarding impacts on fish and wildlife resources. The CDFG

surveyed the stream in February 1990, from the mouth to the headwaters, for a distance of about

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11 km. The survey report indicated that Garrapata Creek had perennial stream flow. Several

barriers were identified which were created by landslides, logjams, and falls/chutes, the latter of

which included a 9 m waterfall. Many barriers were judged to fully block upstream movement

of adult steelhead. Several diversions were identified, two of which led water to trout ponds.

There was an abundance of suitable spawning gravels in the upper stream, which were

inaccessible to steelhead due to the 9 m fall. Sampling for resident rainbow trout was not

conducted there. The lower reaches of the stream contained some spawning riffles and were

relatively free of barriers. Rearing habitat for juvenile steelhead/rainbow trout was of highest

quality in the inaccessible, upper stream area. Sedimentation of decomposed granite was a

pollution problem throughout much of the stream, filling in pools and cementing spawning

gravels. Barriers were also formed by granitic sand being trapped behind stream obstructions.

Juvenile steelhead abundance was estimated, by electrofishing and the mark-and-recapture

method, in three 46 m reaches in the lower and middle main stem, and one 46 m reach in the

Garrapata Creek tributary, Wildcat Canyon Creek. Densities in the main stem, from downstream

to upstream, were 26.0, 1.0, and 13.3 trout/46 m, and only 1 trout/46 m in Wildcat Canyon

Creek. The corresponding mean fork lengths (range) were 107.2 mm (81–191 mm), 163 mm,

and 79.7 mm (50–164 mm), respectively, in Garrapata Creek, and 104 mm in Wildcat Canyon.

Overall, sedimentation, due to logging and improper road grading, was identified as the primary

factor limiting steelhead production in the Garrapata Creek drainage.

Wildcat Canyon Creek

Sedimentation was formally identified as a problem in Wildcat Canyon Creek by the

CDFG as early as 1964, through benthic invertebrate sampling and instream rainbow trout

bioassays (M. L. Johnson, CDFG, unpubl. file report of 28 May 1964). When surveyed briefly

by the CDFG in February 1981, the stream was not regarded as a probable salmonid production

area, and in December 1988, the mean substrate composition, determined from three samples at

one site by sieving sediment through 22.6, 7.95, 2.79, and 0.85 mm screens, was 19%, 8%, 11%,

26%, and 36% (<0.85 mm particles), respectively. The CDFG collected only one juvenile

steelhead in a 46 m reach of the creek, by electrofishing in February 1990 (see Garrapata Creek,

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above).

Granite Canyon Creek Drainage Granite Canyon Creek has evidently not been populated by steelhead within recent

geological history. The CDFG conducted a cursory barrier survey of the stream on 27 February

1981 and found a 4.5 m waterfall at the creek mouth. The presence or absence of resident

rainbow trout above the fall was apparently not investigated.

Kirk Creek Drainage The U.S. Forest Service surveyed Kirk Creek on 13 July 1981, and found that a 4 m

waterfall, located about 1.2 km above the creek mouth at the Pacific Ocean, would block the

upstream migration of steelhead beyond that point. This very small stream had low to

intermittent flow, a high gradient, lacked pools, and overall seemed underdimensioned for

steelhead use. Indeed, no fish were observed between the mouth and the waterfall. The presence

or absence of resident rainbow trout above the waterfall was apparently not investigated.

Limekiln Creek Drainage The main stem of Limekiln Creek is joined by the tributaries, West Fork Limekiln and

Hare Canyon creeks, within 0.8 km from its mouth at the Pacific Ocean. Steelhead only have

access to the lowermost portions of each stream because of natural barriers. The most notable

barrier is a ~20 m waterfall on Limekiln Creek, situated <0.8 km upstream from its confluence

with the tributaries. Because of these natural restrictions on steelhead access within recent

geological history, the limited available information on these three streams is presented

compositely.

The entire portion of the lower drainage accessible to steelhead was surveyed by the

CDFG on 28 August 1961 and 8 September 1961. Spawning areas were noticeably lacking

because of the cementing effect of calcium carbonate precipitates. The stream provided high

quality rearing habitat, in the form of pools and cover. Juvenile steelhead/rainbow trout, 7.5–10

cm in length, were very scarce; the lack of suitable spawning gravel was attributed as the main

limiting factor. Seasonally intense fishing pressure may have also contributed to the apparently

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low juvenile abundance. No past stocking of steelhead/rainbow trout was known.

However, the Limekiln drainage was included in the CDFG’s attempt to develop brown

trout fisheries in Monterey County during the 1950’s and 1960’s. For example, on 8 May 1962,

3,000 brown trout fingerlings were planted in Limekiln Creek below the waterfall barrier; 3,000

in the West Fork Limekiln Creek above barriers to adult steelhead migration; and 6,000 in Hare

Canyon Creek, above steelhead migration barriers (CDFG, unpubl. field notes of 8 May 1962).

A few 10–15 cm long rainbow trout were observed in Hare Canyon Creek where, as below the

barriers, the stream substrate was calcified and only occasional beds of loose pea-size gravel

were available for spawning. Both upper Limekiln and Hare Canyon creeks, above steelhead

barriers, were stocked with an additional 600 brown trout fingerlings each on 23 June 1963 (M.

L. Johnson, CDFG, unpubl. memo. of 17 July 1963).

Survival from these plants was apparently low as only 10 brown trout were captured by

hook-and-line and hand braille when the Limekiln Creek drainage was sampled during 1–2

September 1963 (M. L. Johnson, CDFG, unpubl. memo. of 14 October 1963). In contrast, the

same sampling effort produced 69 juvenile steelhead/rainbow trout, ranging in length from about

5 to 25 cm.

The U.S. Forest Service surveyed Hare Canyon Creek on 17 October 1981, from the Los

Padres National Forest boundary in the lower creek area to 3.2 km upstream. The condition of

the stream seemed much the same as in earlier surveys. Few juvenile steelhead/rainbow trout

were seen. The density of trout, 2.5–15 cm long (mean, 10 cm), was visually estimated at about

20 fish/100 m.

Little Sur River Drainage The Little Sur River drainage may be one of the most productive steelhead rivers south of

San Francisco Bay at this time, given its size (about 103 km2) and condition. The lower drainage

area is private property, while the headwaters are on public lands, primarily the Los Padres

National Forest, that lack roads and trails. Lack of access has kept much of the Little Sur

drainage in a relatively pristine state.

Little fishery management work has been conducted on the Little Sur River, although the

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CDFG has long recognized it as a steelhead production area. In 1965, the CDFG estimated the

annual steelhead spawning run in the Little Sur River at about 500 fish, based on the

observations of local field personnel (California Department of Fish and Game 1965). On 4

August 1988, the CDFG made two electrofishing passes through a 58 m reach of the Little Sur

River to estimate juvenile steelhead abundance with the Seber and Le Cren method. Abundance

(± SD) was estimated at 28 ± 8 trout, or a density of 49 ± 14 trout/100 m. These fish were 50–

148 mm in length (mean ± SD = 78 ± 29 mm; n = 22), with the catch dominated by young-of-

the-year.

Nehlsen et al. (1991) classified the Little Sur River steelhead population as a stock of

special concern.

Malpaso Creek Drainage Malpaso Creek is about 7 km long, the middle third of which is included in Garrapata

State Park. Rischbieter (1990b) surveyed the stream within the park on 4 April 1989. Pools

provided adequate rearing habitat for juvenile steelhead/rainbow trout. Two steelhead migration

barriers were identified: a 1.2 m high diversion dam at the downstream park boundary, and a 2 m

fall created by a logjam about 46 m below the diversion dam. Trout electrofished in the park

were assumed to be resident rainbows. These fish were 58–185 mm in length (mean ± SD = 102

± 31 mm; n = 15), and apparently represented several age classes, including adults. The

presence or absence of juvenile steelhead below the barriers was not investigated.

Resident rainbow trout were also sampled above the diversion dam on 22 August 1990

(D. C. Rischbieter, California Department of Parks and Recreation, unpubl. data). Three

electrofishing passes were made through a reach which produced a catch of 19 trout. These fish

were 35–102 mm in length (mean ± SD = 47 ± 15 mm). In contrast to the 1989 sample,

young-of-the-year were present and dominated the catch.

The original source of the rainbow trout in Malpaso Creek is unclear. As in many of

these small, Big Sur coastal streams with barriers that currently limit or block steelhead access, it

is not known if resident rainbow trout above barriers are what remain of a pre-barrier steelhead

colonization or if they are the result of an undocumented fish transfer by humans. Malpaso

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Creek was reportedly stocked with juvenile steelhead/rainbow trout from nearby San Jose Creek

by Walter Victorine, whose family had a ranch locally (J. G. Williams, CDFG, unpubl. letter of

16 June 1994).

McWay Creek Drainage McWay Creek, a small steep-gradient perennial stream, has evidently not been populated

by steelhead within recent geological history because of a 12 m waterfall at the creek mouth.

Resident rainbow trout were reported in the creek as late as 1984, but none was captured there

during a brief electrofishing survey on 5 April 1989 (Rischbieter 1990c). The Rat Creek wildfire

in 1985 and subsequent heavy storms during the winter of 1985-86 may have extirpated the

trout, or nearly so. As of 1989, the drainage had apparently recovered from these perturbations,

which would allow for the re-expansion or reintroduction of the species.

Mill Creek Drainage Mill Creek, a small, high-gradient perennial stream, was surveyed by the CDFG on 20

July 1961, from the mouth to headwater forks. Spawning gravels were covered with coarse

sand, due at least in part to the effects of previous logging and road building in the drainage.

Pools were also silted, especially in the lower creek. The mainstem creek had only one partial

barrier to upstream migration of adult steelhead created by a log; access to the headwater forks

was limited by natural bedrock falls. There was only one small domestic water diversion in the

lower creek.

Despite the siltation problem in the drainage, at least two consecutive year-classes of

juvenile steelhead/rainbow trout were observed during this survey: 5.0–10.0 cm long trout were

moderately abundant, while those 15 cm long were scarce. Visually-estimated abundances were

very low in the mid and upper sections of the creek, 1–2 trout/100 m, but much greater in the

lower creek, 33–66 trout/100 m. Local residents reported that only a few adult steelhead

ascended the stream during the 1960–61 spawning season, and that juvenile steelhead/rainbow

trout were lightly fished because the maximum length reached was only 12.5–15.0 cm. Several

limits of these small fish were apparently caught from the middle section of Mill Creek during

the 1962 trout season (CDFG, unpubl. field note of 19 November 1962).

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By 1977, gravels in the mid-section of Mill Creek, above the confluence with Lion

Creek, were cemented by calcium carbonate precipitates (B. Graham, CDFG, unpubl. memo. of

4 March 1977). This condition was seen from the mouth to headwaters when the creek was

surveyed by the U.S. Forest Service on 18 September 1981. Siltation was apparently less of a

problem than in 1961 when the CDFG surveyed the stream (c.f. above). There was one partial

migration barrier in the lower creek area created by a log and debris. Juvenile steelhead/rainbow

trout were 2.5–15 cm long (mean ≈ 7.5 cm), and occurred at low visually-estimated densities of

7–13 trout/100 m. The low trout abundance was attributed to poor substrate quality for

spawning and invertebrate food production. The survey report indicated that brown trout had

been planted in Mill Creek in 1961, but apparently a population was not established.

Partington Creek Drainage Partington Creek, a steep-gradient perennial stream along the Big Sur coast, was

surveyed by the CDFG in 1972.

The California Department of Parks and Recreation (CDPR) spot sampled Partington

Creek, both upstream and downstream of Highway 1, by use of electrofishing on 5 April 1989

(Rischbieter 1990c). Juvenile steelhead/rainbow trout were captured at all of three sites.

Compositely, these fish averaged (± SD) about 11 ± 3 cm SL and ranged from about 6 to 20 cm

SL (n = 40). Because the sampling effort was biased toward pools, larger fish may have been

proportionately overrepresented in the catch. Trout captured above a 1.8 m debris dam,

upstream from Highway 1, were most likely resident rainbow trout. The sample collected from

three pools immediately above the creek mouth may have also contained steelhead progeny,

since steelhead apparently have access to the lower stream.

Juvenile steelhead/rainbow trout were observed in lower Partington Creek on 30 August

1993 (R. G. Titus, CDFG, pers. obs.).

Plaskett Creek Drainage Little is known about steelhead in Plaskett Creek, a small perennial stream. The U.S.

Forest Service surveyed lower Plaskett Creek on 15 July 1981. Riffles were abundant but pools

were few, small, and shallow. Cattle were causing streamside vegetation loss, erosion, and

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organic pollution, and were thus considered a major threat to the stream habitat and trout

population. Water was diverted from the creek for domestic use. Juvenile steelhead/rainbow

trout were 2.5–18.0 cm in length (mean ≈ 7.5 cm), and occurred at a low visually-estimated

density of 16 trout/100 m.

The CDFG recognized Plaskett Creek as a viable steelhead stream in 1991 when it denied

an application for private stocking of rainbow trout in the creek (B. Hunter, CDFG, unpubl. letter

of 15 July 1991). The denial was based on the premise of maintaining the genetic integrity of the

native steelhead.

Prewitt Creek Drainage The CDFG surveyed the lowermost 5.6 km of Prewitt Creek on 24 July 1961. A series of

natural bedrock falls and logjams limited steelhead access beyond the junction of the headwater

forks, about 2 km upstream from the mouth. Spawning and rearing habitats for

steelhead/rainbow trout were lacking in the high-gradient upper creek, as there was very little

gravel and only small, shallow, cascading pools. Spawning gravels were also very limited in the

lower creek, but pools were relatively better developed and thus more suitable for steelhead

rearing during low flow periods. Water was diverted from the South Fork Prewitt Creek. Cattle

grazed the area downstream from Highway 1, but no grazing impacts were noted.

The visually-estimated density of juvenile steelhead in the lowermost creek area was 39

trout/100 m. Most fish were young-of-the-year, 7.5–10.0 cm in length; age 1+ trout, ≥ 12.5 cm

in length, were scarce. Few trout were seen in the upper creek. Local residents reported good

fishing for juvenile steelhead/rainbow trout, 15.0–17.5 cm in length, for a short period following

the opening of fishing in the spring. Fishing was also reportedly good for adult steelhead during

“good steelhead years,” presumably meaning in high precipitation years.

On 8 May 1962, 6,000 brown trout fingerlings were planted in Prewitt Creek, in the

headwaters above the steelhead barrier area described above (CDFG, unpubl. field note of 8 May

1962). Many juvenile steelhead/rainbow trout, mostly 2.5–5.0 cm in length, were observed in

the lower creek area, below the barriers; few juveniles were seen between the barriers and the

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headwater forks, and none in the forks.

Survival of brown trout planted in 1962 was apparently low as none was captured by

hook-and-line or hand braille when the creek was sampled during 1–2 September 1963 to

evaluate the plant (M. L. Johnson, CDFG, unpubl. memo. of 14 October 1963). However,

juvenile steelhead/rainbow trout were caught, ranging in length from 5 to 15 cm.

The U.S. Forest Service surveyed the lowermost 4.8 km of Prewitt Creek on 16 July

1981. The condition of the stream and its use by steelhead seemed to be much the same as when

surveyed by the CDFG in 1961 (see above), with one notable exception. Cattle grazing in the

area downstream from Highway 1 was causing streamside vegetation loss, erosion, and organic

pollution, and was thus considered a major threat to habitat quality and steelhead production in

the lower creek. The estimated average density of juvenile steelhead/rainbow trout ranged from

49 trout/100 m in the lower creek, to 39 trout/100 m in the mid-section, to 33 trout/100 m in the

headwater south fork. Overall, the trout were visually-estimated at 2.5–20.0 cm in length, and

averaged 10.0–12.5 cm among sections.

Rocky Creek Drainage No detailed historical information was discovered regarding the steelhead population in

Rocky Creek, a small, perennial stream with a cobble and boulder dominated substrate. There

was mention in a CDFG document of steelhead migrating up Rocky Creek to spawn following

sufficient rainfall (CDFG, unpubl. letter of 8 November 1971).

Steelhead use of Rocky Creek is corroborated by a local resident who has fished and

observed the stream since the late 1940’s (J. G. Williams, Carmel, CA, unpubl. letter of 16 June

1994). Three length-frequency modes of juvenile steelhead/rainbow trout were apparent, as

observed in summer: young-of-the-year about 5 cm long in the shallow downstream end of

pools, yearling fish about 10 cm long, and a less distinct group at about 15 cm. Trout over 23 cm

long were rare, and fish >15 cm long occurred mainly in the larger pools. Angling for fish >13

cm long was very productive. Winter observations were few but adult steelhead were seen in the

stream. There was a 1.5 m dam in the mid-creek area from about 1930 to 1980, but this structure

apparently was not a complete migration barrier as an adult steelhead was seen upstream from it.

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Natural waterfalls in the upper creek area, however, block steelhead access to the headwaters.

Resident rainbow trout occur above the falls.

Although no inference could be drawn regarding the adult steelhead population trend at

Rocky Creek, the relative abundance of juvenile steelhead/rainbow trout has dropped noticeably.

This observed reduction has been associated with increased water diversion and silt input from

roads in the upper watershed. The amount and quality of rearing habitat, especially in the form

of pools, has decreased, thus exacerbating the effects of the recent six-year (1986-87 to 1991-92)

drought when stream flow fell below 3 L/s.

Dettman (1989) calculated an index of the quality and quantity of juvenile steelhead

rearing habitat in two reaches of Rocky Creek, at three stream flows ranging from 4 to 18 L/s.

The rearing index increased with increasing flow and, according to the model, the optimum

rearing index would have been observed at some flow higher than 18 L/s. In addition to low

summer flow, the degree of cobble embeddedness from sand deposition was also determined to

be a major constraint to juvenile steelhead rearing habitat quality. The source of erosion

responsible for the input of sand was not identified, but was mentioned to be usually associated

with road construction. No actual observations of steelhead habitat use or abundance relative to

stream flow were included in the report.

Salinas River Drainage, Including Portions in San Luis Obispo County Historically, steelhead have used the headwaters of the Salinas River, and the tributaries

draining the western side of the basin (see below), for spawning and rearing. The lower main

stem serves primarily as a migration corridor, when sufficient runoff provides a connection to the

Pacific Ocean. Barclay (1975) described briefly the unsuitability of the valley portion of the

mainstem Salinas River as spawning and rearing habitat for juvenile steelhead, because of the

sandy and silty substrate, and high water temperature and lack of flow in summer. Although

Snyder (1913) found juvenile steelhead/rainbow trout at three locations in the main stem from

near Salinas to Soledad, these fish were probably emigrating smolts; trout found in the main

channels of the rivers were “apt to be rather poor in quality”, perhaps indicating low condition

factor, and “usually light silvery in color”, both of which are typical smolt characteristics.

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Hubbs (1947) found no steelhead at six sampling locations in the lowermost 4.8 km of the river

on 3 and 11 August 1946. Sampled habitats had muddy or sandy bottoms and semi-ponded to

slow-moving water.

Salinas Dam, which forms Santa Margarita Lake (formerly Salinas Reservoir) in the

upper Salinas River, was completed in 1942. Before the dam was built, adult steelhead migrated

as far upstream as Pozo, and occasionally farther during winters of exceptionally high rainfall (F.

W. Hecker, CDFG, unpubl. field corr. of 9 May 1947). The number of steelhead reaching the

dam each year varied greatly and was apparently a positive function of the amount of rainfall; no

steelhead reached the dam during the winter of 1946-47.

Based on available information, it was impossible to estimate even the relative magnitude

of historical steelhead runs in the Salinas River drainage. Snyder (1913) wrote only that “large

numbers” of steelhead entered all the streams tributary to Monterey Bay, including the Salinas

River drainage. By the mid-1950’s, adult steelhead spawning runs occurred irregularly and the

population supported only a “meager fishery” (Pelgen and Fisk 1955). As of 1965, the CDFG

estimated the annual steelhead spawning run in the Salinas drainage at little more than about 500

fish, based on the observations of local field personnel (California Department of Fish and Game

1965).

Barclay (1975) found that viable rainbow trout habitat still existed in the upper mainstem

Salinas River, above the Highway 58 bridge.

Impoundment and diversion of surficial stream flow, groundwater pumping, and blocked

access to perennial headwaters have caused the decline of Salinas River steelhead. The integrity

of the natural streambed has also been compromised by extensive extraction of streambed

materials, as witnessed through documentation in the CDFG files. As a result of these negative

impacts, the Salinas River steelhead was classified as having a moderate risk of extinction by

Nehlsen at al. (1991).

Arroyo Seco and Tributaries

The Arroyo Seco is the first major spawning tributary to which steelhead have access as

they enter the Salinas River drainage from the Pacific Ocean. Snyder (1913) found juvenile

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steelhead/rainbow trout in the Arroyo Seco at 3.2 km, 6.4 km, and 9.7 km above the confluence

with the Salinas River, but not at 1.6 km. He also noted observations of carcasses of large

steelhead post-spawners along the Arroyo Seco.

By the 1950’s, the CDFG de-emphasized steelhead management in the Arroyo Seco and

elsewhere in the Salinas drainage because of plans for increased development of water resources

(Pelgen and Fisk 1955). Attempts were instead made to enhance resident trout fisheries through

extensive planting of both rainbow and brown trout. The brown trout program was especially

emphasized, beginning with a plant of about 3,400 nearly catchable-size fish in September 1953

(CDFG, unpubl. field notes of 26 September 1953).

Creel censuses and electrofishing surveys were conducted over the years to evaluate the

brown trout stocking program, during which data were also collected on wild juvenile

steelhead/rainbow trout. For example, 1,051 juvenile steelhead/rainbow trout were caught by

anglers during 1–2 May 1954 (E. A. Best, CDFG, unpubl. intraoffice corr. of 5 May 1954).

These fish averaged 17.0 cm (range, 8.1–29.5 cm), the majority of which were light and silvery

in color and presumed to be hatchery fish. However, the observed coloration also suggests the

presence of steelhead smolts in the catch, and appropriately so considering the time of year.

Darkly colored fish with a prominent red lateral stripe were regarded as wild rainbow trout;

some of these fish were gravid females.

The CDFG electrofished two 76 m sections of the Arroyo Seco on 4 November 1954 (E.

A. Best, CDFG, unpubl. intraoffice corr. of 22 November 1954). In a section at Santa Lucia

Memorial Park, 48 juvenile steelhead/rainbow trout were captured that ranged in length from 7.9

cm to 22.1 cm. In a section located about 1.6 km below Rooster Creek, 34 juvenile

steelhead/rainbow trout were captured, 7.1 cm to 23.6 cm in length.

The CDFG surveyed about 5.5 km of the Arroyo Seco on 6 June 1957, from Santa Lucia

Memorial Park to the headwaters. A visually estimated 15% to 20% of the survey area consisted

of spawning grounds for trout, most of which was in the lower half of the area. The stream was

cascading and provided an abundance of high-quality rearing habitat in the form of pools and

cover. No barriers or diversions were observed. Both wild juvenile steelhead/rainbow trout and

planted catchable rainbow trout were observed and caught on hook-and-line, with only the

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former ranging into the very high-gradient headwaters. The survey report indicated that, in

addition to catchable rainbow trout, juvenile steelhead had also been planted previously in the

Arroyo Seco, but no such records were discovered.

Memoranda and field notes contained in the CDFG files indicated that the rotary fish

screen at the Greenfield Water District’s diversion on the Arroyo Seco was persistently

dysfunctional over the years. Observed documents regarding this problem ranged in dates from

12 May 1948 to 26 April 1966. The diversion is located on the Arroyo Seco about 3.2 km below

Santa Lucia Memorial Park. No reliable estimates were made as to how many juvenile

steelhead/rainbow trout may have been lost annually in the diversion.

On 30 March 1968, about 200 juvenile steelhead, 15 cm to 25 cm in length, were rescued

from the desiccating lower Arroyo Seco at the Thorne Road crossing, and released farther

upstream where presumably perennial flow occurred (R. Azbill, CDFG, unpubl. field corr. of 5

April 1968). Steelhead continued to be mentioned in CDFG file documents as a viable fishery

resource in the Arroyo Seco as of 1978 (M. L. Johnson, CDFG, unpubl. letter of 17 February

1978). An estimated 300 juvenile steelhead/rainbow trout, about 7.5 cm to 15 cm in length, died

in the Arroyo Seco at the Arroyo Seco Campground on 28 August 1979. Temperature stress was

believed to be the cause of death. No juvenile steelhead were found in the lower Arroyo Seco on

13 September 1979, when several locations were spot-checked by use of electrofishing from the

Greenfield Bridge to the Tassajara Creek confluence (S. Recknagel, CDFG, unpubl. memo. of 14

September 1979). Hatchery rainbow trout continued to be planted in the Arroyo Seco as of 7

June 1980, when 4,000 fish (@ 551/kg) were stocked in the headwaters by the Southern

Monterey County Sportsmen’s Association.

The USFS surveyed the headwaters of the Arroyo Seco during 3–4 November 1981, from

Indian Station to a point 6.4 km upstream. The characteristics and condition of this portion of

the stream appeared to be much the same as when surveyed by the CDFG in June 1957 (see

above). Juvenile steelhead/rainbow trout were observed in average visually-estimated densities

of about 66 trout/100 m in the lower survey area, and about 39 trout/100 m in the upper survey

area. The fish ranged in length from about 2.5 cm to 20 cm, and averaged about 13 cm.

During 19–26 February 1983, 16 adult steelhead were landed at or below the Thorne

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Road crossing on the lower Arroyo Seco (J. Barton, CDFG, unpubl. memo. of 11 January 1984).

The road crossing created an upstream-migration barrier for which a fish ladder was needed.

One adult, which measured about 75 cm in length, was also landed in this area on 2 January

1984, and four more steelhead were reportedly caught in the Arroyo Seco (M. L. Johnson, CDFG

unpubl. memo. of 9 January 1984).

The CDFG surveyed by use of electrofishing five sections of the Arroyo Seco

downstream from the Santa Lucia Memorial Park, during 8–25 September 1992 (K. D. Murphy,

CDFG, unpubl. stream survey data). Mean (± SD) section length was 96 ± 5 m. Juvenile

steelhead/rainbow trout had section-specific mean lengths of approximately 9 to 31 cm FL, and

an overall mean length of about 10 ± 5 cm FL (n = 83); only one fish was >25 cm FL. Section-

specific densities averaged 18 ± 13 trout/100 m (range, 1–38 trout/100 m), based on abundance

estimates made with the three-pass depletion method.

During 26–29 August 1993, the CDFG continued its survey by electrofishing four more

sections of the Arroyo Seco, this time upstream of Santa Lucia Memorial Park (K. D. Murphy,

CDFG, unpubl. stream survey data). Mean (± SD) section length was 89 ± 10 m. Section-

specific mean lengths of juvenile steelhead/rainbow trout had a small range (7–8 cm FL) as all

sections were dominated numerically by young-of-the-year trout. The overall mean length was

about 8 ± 3 cm (n = 410), and there were no juvenile steelhead/rainbow trout >25 cm FL.

Section-specific densities averaged 141 ± 29 trout/100 m (range, 118–182 trout/100 m), based

on abundance estimates made with the three-pass depletion method.

Adult steelhead were observed in the Arroyo Seco during the 1992-93 spawning season

(J. Nelson, CDFG, pers. comm. of 17 March 1993). The nearly eight-fold increase in mean

density of juvenile steelhead/rainbow trout between the 1992 and 1993 electrofishing surveys,

with a pronounced dominance of age-0 fish, strongly suggested successful steelhead spawning;

the 1992 data were not indicative of an adult resident rainbow trout population of the magnitude

to result in such high young-of-the-year densities.

The Arroyo Seco headwater tributary, Lost Valley Creek, and its tributaries, Higgins and

Zigzag creeks, have also historically provided high quality habitat for steelhead and rainbow

trout. Nearly 10 km of Lost Valley Creek were surveyed by the CDFG during the mid-1930’s.

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The stream substrate was dominated by gravel which provided spawning habitat for steelhead

and rainbow trout throughout the survey area. No migration barriers or diversions were

observed. Juvenile steelhead/rainbow trout were present in the stream, all of which were the

result of natural propagation as no known stocking had occurred.

The uppermost 2.4 km of Higgins Creek were surveyed by the CDFG on 7 June 1957.

This cascading portion of the stream contained high quality spawning and rearing habitat for

rainbow trout, although no fish were seen. One 4.5 m high bedrock and boulder waterfall was

located within the survey area, which may historically have limited the upstream dispersal of

steelhead/rainbow trout from below, thus accounting for their apparent absence. No past

stocking was known, although the stream was later included in an extensive brown trout planting

program that was undertaken in southern Monterey County during the 1950’s–early 1960’s. For

example, 4,160 brown trout fingerlings (@ 564/kg) were planted in Higgins Creek on 27 August

1959.

CDFG personnel conducted an angling survey of Higgins Creek on 17 May 1966, from

Pelon Camp to a point about 0.8 km upstream. This section was downstream from the fishless

section surveyed in 1957 (see above), and also contained suitable spawning and rearing habitat

for rainbow trout. Juvenile steelhead/rainbow trout up to about 20 cm in length were captured

on hook-and-line at an approximate catch rate of 1.7 trout/hr. Young-of-the-year

steelhead/rainbow trout were also observed.

As part of the same excursion, Lost Valley Creek was fished on 18 May 1966, from Lost

Valley Camp to near the Zigzag Creek confluence. Spawning substrate may have been limited,

but rearing habitat in the form of pools and cover seemed extensive. Compared to Higgins

Creek, the abundance of juvenile steelhead/rainbow trout was relatively high, and the catch rate

on hook-and-line was about 10 trout/hr. Observed young-of-the-year were about 2.5 cm in

length, while captured trout ranged up to about 25 cm.

The mean (± SD) density of juvenile steelhead/rainbow trout in Lost Valley, Higgins,

and Zigzag creeks was 33 ± 25 trout/100 m, 53 ± 5 trout/100 m, and 43 trout/100 m,

respectively, when sampled during 1970–71 as part of a survey of steelhead standing crops

between San Francisco and San Luis Obispo (L. K. Puckett, CDFG, unpubl. memo. of 30

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December 1971). Juvenile steelhead/rainbow trout abundance was highly variable (c.v. = 114%)

throughout this region; densities in the Arroyo Seco tributaries were well below the overall

average of 155 ± 178 trout/100 m. Trout abundance was estimated by use of electrofishing and

the two-pass depletion method in several randomly-selected 30.5 m sections per 1.6 km of

stream.

The CDFG surveyed Lost Valley Creek and the Zigzag Creek system in August 1978,

following the Marble Cone fire (P. Chappell, CDFG, unpubl. memo. of 11 June 1979). It was

reported that Lost Valley Creek was in generally good condition, and that the stream supported

an excellent rainbow trout fishery. Rainbow trout were sampled by hook-and-line, and all

captured fish were infested with encysted metacercaria of the monogenetic trematode, Neascus, a

condition commonly referred to as “black spot disease”. No trout were observed in the Zigzag

headwater tributary, Camp Creek, nor in Zigzag Creek itself until below the fourth waterfall

about 0.4 km upstream from the confluence with Lost Valley Creek. Water conditions for trout

were noted as excellent.

Hatchery rainbow trout continued to be planted in Lost Valley Creek as of 7 June 1980,

when 3,000 fish (@ 551/kg) were stocked by the Southern Monterey County Sportsmen’s

Association.

The Arroyo Seco headwater tributary, Tassajara Creek, and its tributary, Willow Creek,

have also historically provided high quality habitat for steelhead and rainbow trout. Tassajara

Creek, at about 0.4 km above Tassajara Hot Springs, was surveyed by the CDFG on 29 June

1945. The survey area contained high quality spawning and rearing habitats for steelhead, the

latter in the form of pools and cover. The report indicated that the stream was used extensively

by steelhead for natural propagation, and juvenile steelhead were observed.

Willow Creek was surveyed by the CDFG in its entirety on 5 June 1957. Spawning

gravels were scarce in the perennial, cascading stream, but rearing habitat in the form of pools

and cover was abundant and of very high quality. A 3-m high bedrock fall, located in the upper

half of the creek, blocked upstream migration under low-flow conditions, but may have been

passable at high flows. No diversions were seen. Juvenile steelhead/rainbow trout were scarce

in abundance, but those observed ranged in length from about 5 to 15 cm and were noted to be

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wild progeny and in good condition. Willow Creek had been stocked with 5,000 each of

juvenile steelhead and rainbow trout in 1940, and other plants had probably been made during

the late-1930’s and early 1940’s for which records were not found.

Willow Creek was used as a test stream in the CDFG’s development of brown trout

fisheries in Monterey County during the 1950’s and 1960’s. Five 76-m sections were sampled

by use of electrofishing during 27–28 April 1963 to determine the approximate size and structure

of the wild trout population prior to making new plants of brown trout fingerlings (R. J. Hansen,

CDFG, unpubl. memo. of 14 May 1963). All captured fish were juvenile steelhead/rainbow

trout, which had section-specific mean lengths of from 9.4 to 17.5 cm, and an overall mean

length of 11.4 cm (overall range, 2.8–25.4 cm). Conservative estimates of section-specific

densities were low, and averaged 14 trout/100 m (range, 9–20 trout/100 m). There was no

mention of smolting trout, although trout ≥ 18 cm long appeared to have relatively low condition

factors, which is a typical smolting characterisitic. Alternatively, these fish may also have been

post-spawners. Steelhead use of the stream at the time of this survey appeared to be light or non-

existent, as the low population density was more indicative of a resident rainbow trout

population, even assuming a high angler-harvest rate (e.g. M. L. Johnson, CDFG, unpubl. admin.

report of 13 April 1964).

Following a plant of 5,000 brown trout fingerlings on 23 July 1963, the same five test

sections of Willow Creek were electrofished again on 25 April 1964 (R. J. Hansen, CDFG,

unpubl. memo. of 7 May 1964). Juvenile steelhead/rainbow trout had section-specific mean

lengths of from 9.1 to 10.7 cm, and an overall mean length of 9.9 cm (overall range, 5.6–15.5

cm). Conservative estimates of section-specific densities averaged 24 trout/100 m (range, 12–33

trout/100 m). The overall estimated density of juvenile steelhead/rainbow trout in April 1965

was the same as in April 1963, about 14 trout/100 m (M. L. Johnson, CDFG, unpubl. memo. of 9

July 1965). This study showed that the survival of brown trout fingerlings was low, with a

correspondingly low return to the creel, and no apparent impact on the wild steelhead/rainbow

trout population.

The USFS surveyed the lowermost portions of Tassajara and Willow creeks on 5

November 1981, from the mouth at the Arroyo Seco to 1.2 km below Willow Springs

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Campground. No significant change could be discerned in the characteristics or quality of the

streams as steelhead/rainbow trout production areas, as compared with earlier CDFG surveys

(see above). The visually-estimated density of juvenile steelhead/rainbow trout was greater in

lower Tassajara Creek (about 66 trout/100 m) than in lower Willow Creek (about 16 trout/100

m). The trout were also longer on average in Tassajara (15 cm; range, 2.5–25 cm) than in

Willow Creek (10 cm; range, 2.5–15 cm).

The Arroyo Seco and its tributaries may support the only persistent remnants of Salinas

River steelhead (K. R. Anderson, CDFG, pers. comm. of 9 July 1992).

Atascadero Creek

The Salinas River tributary, Atascadero Creek in San Luis Obispo County, was used

historically by steelhead. Juvenile steelhead/rainbow trout were abundant in Atascadero Creek

when surveyed by Barclay (1975). The creek as well as Atascadero Lake, an impoundment on

the creek, have been stocked with catchable rainbow trout over the years, which indicates that

the system does indeed contain trout habitat. The Salinas River has become an increasingly

unreliable migration corridor, and the creek itself has been altered by road/bridge construction

and extraction of streambed materials, as evidenced by documents contained in the CDFG files.

The status of the Atascadero Creek steelhead population has not been recently assessed, but

steelhead use of the creek is likely very limited by the habitat degradation that has occurred

throughout the system, including the creek itself.

Nacimiento River and Tributaries

The Nacimiento River was one of the most important spawning and rearing tributaries for

Salinas River steelhead. Snyder (1913) found juvenile steelhead/rainbow trout at all of three

sampling stations in the Nacimiento, from the foothill to mountainous portions of the drainage.

He also noted observations of large steelhead carcasses along the river, and that fishing for

juvenile steelhead/rainbow trout was especially good in the upper Nacimiento. There was

apparently a “good run” of steelhead in the Nacimiento during the winter of 1950-51 (CDFG,

unpubl. field notes of 24 January 1951).

The dam forming Nacimiento Reservoir on the Nacimiento River in San Luis Obispo

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County was completed in the fall of 1956, and impoundment began that winter. The dam is

located about 11.3 km upstream from the confluence with the Salinas River. With construction

of the dam which lacked provisions for fish passage, steelhead no longer had access to historic

spawning and rearing habitats in the upstream portions of the system.

No wild juvenile steelhead/rainbow trout were seen or captured during cursory surveys of

the upper river (above the reservoir) during 1960–61, following rotenone treatment in 1956-57 to

remove non-game fishes (M. R. Schreiber, CDFG, unpubl. intraoffice corr. of 28 June 1960; R.

N. Hinton, CDFG, unpubl. intraoffice corr. of 2 January 1962). In addition to being stocked with

catchable rainbow trout, the upper Nacimiento River was included in the CDFG’s development

of brown trout fisheries in Monterey County; for example, about 1,200 brown trout fingerlings

were stocked in the upper river on 23 June 1963 (M. L. Johnson, CDFG, unpubl. memo. of 17

July 1963). When the upper river was fished between Redwood and ABC camps by CDFG

personnel in 1971, brown trout were captured above a 7.6-m high waterfall barrier, and rainbow

trout below (L. K. Puckett, CDFG, unpubl. memo. of 13 May 1971). Trout abundance was low,

and low summer stream flow was mentioned as a likely limiting factor to population growth.

The upper Nacimiento River within the Los Padres National Forest was surveyed by the

USFS during 2–3 September 1981. Stream flow was interrupted in the lower and middle

portions of the survey area, where rainbow trout oversummered in perennial pools. These fish

occurred in visually-estimated abundances of about 33 and 20 trout/100 m in the lower and

middle sections, respectively, and averaged about 5 cm in length (range, 2.5–13 cm). Thus, most

trout were young-of-the-year and natural reproduction was successful. Stream flow was very

low but continuous in the upper survey section, where rainbow trout occurred at a visually-

estimated abundance of about 39 trout/100 m, and averaged about 10 cm in length (range, 2.5–20

cm). Brown trout were again found only above the waterfall barrier mentioned above.

The CDFG surveyed by use of electrofishing nine sections of the upper Nacimiento

within the Los Padres National Forest, during 21 July–20 August 1992 (K. D. Murphy, CDFG,

unpubl. stream survey data). Mean (± SD) section length was 98 ± 8 m. Juvenile

steelhead/rainbow trout had section-specific mean lengths of approximately 8 to 12 cm FL, and

an overall mean length of about 8 ± 3 cm FL (n = 525). Section-specific densities averaged 59 ±

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66 trout/100 m (range, 0–160 trout/100 m), based on abundance estimates made with the three-

pass depletion method.

A catchable rainbow trout planting program in the lower river (below the dam) was

initiated on a trial basis in 1963 (Johnson 1966) and continued through at least 1987. One

resident rainbow trout, but no juvenile steelhead, were captured in the lower river during

January–March 1977 (Corson and Simas 1977). The Nacimiento River was still mentioned as a

viable steelhead water in CDFG file documents dealing with environmental impacts from 1986

and 1988. Steelhead use of the lower Nacimiento River is dependent upon the presence of a

migration corridor in the main stem Salinas River, and the current presence/absence of steelhead

is not known.

Prior to the construction of Nacimiento Reservoir, steelhead used the Nacimiento River

tributary, Las Tablas Creek, for spawning and rearing. The creek currently flows into one of the

main arms of Nacimiento Reservoir. Las Tablas Creek was surveyed by the CDFG in its entirety

on 25 March 1966, for a distance of about 40 km. The creek contained suitable spawning

gravels for steelhead/rainbow trout, and rearing habitat in the form of pools and cover, including

undercut banks. Overall, the habitat was rated highly. No barriers or diversions were seen. The

lower half or so of the stream was polluted with heavy metal effluents, from both active and

abandoned mines of the Buena Vista Mining Company. This portion of the stream also became

intermittent during the summer. Naturally-propagated rainbow trout, about 7.5–30.5 cm in

length, occurred in the upper half of the stream, at a visually-estimated density of about 12

trout/100 m. Local residents reported that rainbow trout migrated from the reservoir into the

lower stream area during spring. These fish either returned to the reservoir as summer

approached, or died, due to the effects of reduced stream flow and pollution.

Old Negro Fork, a tributary in the extreme headwaters of the Nacimiento River in

Monterey County, was also recognized as a steelhead production area prior to the construction of

Nacimiento Reservoir (W. A. Evans, CDFG, unpubl. memo. of 14 June 1950). The stream was

stocked with catchable rainbow trout at that time.

When surveyed by the CDFG following dam construction on 15 October 1961, the

density of juvenile steelhead/rainbow trout was very low (visually estimated at about 49

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trout/100 m), and their distribution was restricted to below a 3-m high bedrock barrier located

about 1.6 km upstream from the confluence with the Nacimiento. The trout were about 6.5–15

cm long. Other bedrock and boulder barriers were found in the headwaters of the creek system.

Spawning gravel may have been limited, but rearing habitat appeared to be adequate for juvenile

steelhead and young rainbow trout. The stream was observed under very low flow conditions,

following 3 yr of drought.

In addition to previous plants of catchable rainbow trout, the Old Negro Fork was

included in the CDFG’s development of brown trout fisheries in Monterey County; for example,

about 1,200 brown trout fingerlings were stocked, both above and below the falls, on 23 June

1963 (M. L. Johnson, CDFG, unpubl. memo. of 17 July 1963).

The CDFG surveyed by use of electrofishing four sections of the Old Negro Fork, from

the Ponderosa Campground to about 1.1 km upstream, during 18 August–10 September 1992 (K.

D. Murphy, CDFG, unpubl. stream survey data). Mean (± SD) section length was 94 ± 2 m.

Section-specific mean lengths of juvenile steelhead/rainbow trout had a small range (8–9 cm FL)

as all sections were dominated numerically by young-of-the-year trout. The overall mean length

was about 9 ± 4 cm (n = 502), and there were no juvenile steelhead/rainbow trout >25 cm FL.

Section-specific densities averaged 144 ± 69 trout/100 m (range, 83–233 trout/100 m), based on

abundance estimates made with the three-pass depletion method.

The CDFG re-surveyed the same four sections of the Old Negro Fork during 3–5 August

1993 (K. D. Murphy, CDFG, unpubl. stream survey data). Mean (± SD) section length was 95

± 4 m. Section-specific mean lengths of juvenile steelhead/rainbow trout ranged from about 8 to

10 cm FL; thus, as in 1992, all sections were dominated numerically by young-of-the-year trout.

The overall mean length was again about 9 ± 4 cm (n = 750), and only two juvenile

steelhead/rainbow trout >25 cm FL were captured. Section-specific densities averaged about 1.5

times greater than in 1992 (c.f. above), at 217 ± 57 trout/100 m (range, 148–286 trout/100 m),

based on abundance estimates made with the three-pass depletion method.

Paso Robles Creek and Tributaries

Although spawning areas were observed, no juvenile steelhead or other fishes were seen

in Paso Robles Creek during a January 1957 CDFG survey. Insufficient flow for steelhead

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migration in the Salinas River was noted as a primary problem. Local residents reported that

steelhead entered the Paso Robles drainage in 1955 and 1957-58. In a CDFG survey report from

May 1960, juvenile steelhead, about 5 cm in length, occurred at an estimated minimum density

of 4–10 trout/pool. Spawning success appeared to be high, and rearing occurred in shaded,

isolated pools as stream flow receeded in summer. The sport fishery was minor due to limited

access to private property, and a 69 cm steelhead was reportedly caught on hook-and-line the

previous season. Catostomids and cyprinids were also present in the stream at very high

densities. The stream has been altered as a result of bridge construction, diversions, and

extraction of streambed materials, and various tributaries have been impounded. Juvenile

steelhead/rainbow trout were abundant in Paso Robles Creek when surveyed by Barclay (1975).

Jack Creek is a main tributary to Paso Robles Creek which has historically also

functioned as a steelhead spawning and rearing stream. Such mention was made in the report of

a May 1960 CDFG survey of the stream. However, no juvenile steelhead were captured during a

CDFG electrofishing survey in November 1973. It was reported that in the 1950’s, large

numbers of steelhead spawned in this stream, but not in recent years. One substantial migration

barrier and several pumping stations were noted. Two adult steelhead were captured in Jack

Creek in June 1975; one measured 71 cm FL and weighed nearly 4 kg, the other was about 41

cm in length (San Luis Obispo Telegram-Tribune, 18 June 1975). Juvenile steelhead/rainbow

trout were limited in abundance in Jack Creek when surveyed by Barclay (1975). The stream

has been altered by diversions, the construction of small reservoirs, and extraction of streambed

materials, as evidenced by documents contained in the CDFG files.

Santa Rita Creek is another major tributary to Paso Robles Creek. It is comprised of flow

from its north and south forks. When surveyed by the CDFG in May 1960, spawning areas were

present in the main stem and both forks, one diversion pump was in operation, and no barriers

were noted. Juvenile steelhead, 5 cm in length, were present in the main stem and lower north

fork at a density of 4–5 trout/pool. Permanent, well-shaded pools provided summer rearing

habitat. Catostomids and cyprinids were present in very high densities. The dam at the Santa

Rita Ranch was completed in 1965, which blocked any potential upstream movement of

steelhead spawners. By November 1973 when the stream was next surveyed by the CDFG,

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steelhead were unable to reach the Paso Robles drainage because of lack of a migration corridor

by way of the Salinas River. No juvenile steelhead/rainbow trout were captured by use of

electrofishing, although seven other species of fish were present. Apparently, hatchery rainbow

trout were unsuccessfully stocked in the reservoir at the Santa Rita Ranch for several years.

Juvenile steelhead/rainbow trout were limited in abundance in Santa Rita Creek when surveyed

by Barclay (1975).

San Antonio River and Tributaries

The San Antonio River was one of the most important spawning and rearing tributaries

for Salinas River steelhead. Snyder (1913) found juvenile steelhead/rainbow trout at both of two

sampling stations in the San Antonio, near the mission and in the mountains. He also noted that

fishing for juvenile steelhead/rainbow trout was especially good in the upper reaches of the San

Antonio River system.

Rainbow trout were present in the upper San Antonio River when surveyed by the CDFG

during the mid-1930’s. Spawning grounds were scattered in distribution, and the presence of

migration barriers was noted. Early CDFG records also showed that the San Antonio steelhead

population was supplemented with 10,000 juveniles in each of 1931 and 1932, and 15,000 (@

1,764/kg) from the Brookdale Hatchery in 1938. In addition, 60,000 hatchery rainbow trout

were planted during 1930–32, and about 235,000 brown trout during 1930–36.

Evidently, the San Antonio River was used by local CDFG personnel as an index of the

steelhead run in the Salinas River; a few steelhead entered the San Antonio during the winter of

1949-50, but none had been seen as of late January 1951 (CDFG, unpubl. field notes of 24

January 1951). A local resident reportedly saw four adult steelhead ascending the stream during

the winter of 1957-58 at the Merle Ranch, near the boundary of the Los Padres National Forest

and Hunter Liggett Military Reservation, in the upper San Antonio (S. C. Smedley, CDFG,

unpubl. field notes of 4 September 1958). In addition, “trout water” was said to begin about 1.6

km upstream from that point. The CDFG had otherwise observed that steelhead ascended the

San Antonio in all years when rainfall was sufficient to provide continuous stream flow to the

Salinas River; and that resident rainbow trout occurred in the headwaters to within about 5 km

above the ranch (W. A. Evans, CDFG, unpubl. intraoffice. corr. of 19 November 1958).

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About 8 km of the lower San Antonio downstream from Pleyto Bridge was surveyed by

the CDFG on 7 May 1959. Spawning and rearing habitats for steelhead were nonexistent, as the

stream channel was braided, the substrate was mostly sand, and pool development was poor. No

juvenile steelhead/rainbow trout were seen. Nor were any found on 10 May 1960 in the

uppermost 6.5 km of the stream contained within the Hunter Liggett Military Reservation (M. R.

Schreiber, CDFG, unpubl. intraoffice corr. of 13 May 1960).

The results of a CDFG survey conducted during 12–13 September 1961 confirmed earlier

surveys, and provided a general overview of the distribution of steelhead/rainbow trout habitat in

the San Antonio system, and its use by the species. The stream was surveyed from about 2.0 km

upstream from Fresno Camp in the headwaters, downstream to Pleyto Bridge, for a total distance

of about 74 km. Stream flow was minimal in the headwaters, and nonexistent downstream from

the Merle Ranch. Essentially, gravel, pool, cover, and water quality conditions considered

suitable for steelhead/rainbow trout spawning and rearing existed only in the headwaters,

upstream from the Merle Ranch. A 1.2-m high flashboard dam at the ranch created a migration

barrier; water was also diverted from the stream at this point. Rainbow trout and brown trout

were present in the Fresno Camp area. In a related document, it was reported that the owner of

the Merle ranch planted hundreds of hatchery rainbow and brown trout into the San Antonio

River annually, upstream from the flashboard dam (R. L. Moore, CDFG, unpubl. memo. of 26

October 1961).

As on the Nacimiento and upper mainstem Salinas rivers, the San Antonio River was also

developed for its water resources, and a dam was constructed in the lower river which began

storing runoff during the winter of 1965-66. The pattern of flow releases from the dam was not

predicted to provide perennial flow conditions in the lowermost river, and the CDFG decided

against developing a fishery downstream from the dam (R. J. Hansen, CDFG, unpubl. memo. of

4 September 1963).

Prior to impoundment, the CDFG conducted a survey of the entire San Antonio drainage

to determine the necessity of chemical treatment to eradicate non-game fish species. Stream

surveys were made during July–September 1965 which resulted in a relatively detailed

description of the distribution of steelhead/rainbow trout habitat and its use by the species (M. L.

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Johnson, CDFG, unpubl. file report of 10 September 1965). The following areas lacked suitable

spawning and rearing habitats, and were uninhabited by juvenile steelhead/rainbow trout: the

mainstem San Antonio, from the confluence with the Salinas River upstream to the Merle Ranch;

and the tributaries, Jolon Creek and Mission Creek, with its tributary, Coleman Creek. Two

tributaries, Wizard Gulch and Forest Creek, may have supported some spawning but lacked the

stream flow to provide juvenile rearing habitat, and no fish were seen in these streams.

The lowermost mainstem tributary to contain rainbow trout was Bear Canyon Creek,

where these fish ranged in size from about 2.5 to 12.5 cm at a visually estimated density of about

10 trout/100 m. The main stem upstream from the Merle Ranch contained rainbow trout (2.5–25

cm long, @ ~82 trout/100 m), as did an unnamed headwater tributary (2.5–20 cm long, @ ~13

trout/100 m) and the tributary, Salsipuedes Creek (7.5–15 cm long, @ ~16 trout/100 m). The

North Fork San Antonio River contained rainbow trout (2.5–20 cm long, @ ~13–16 trout/100 m)

from the confluence with the main stem at the Merle Ranch, to the headwaters. Several North

Fork tributaries also supported rainbow trout, including: Rattlesnake Creek (5–12.5 cm long, @

~3 trout/100 m) and its tributary, Pinal Creek (7.5–12.5 cm long, @ ~16 trout/100 m); Sycamore

Creek (5–7.5 cm long, @ ~26 trout/100 m); Carrizo Creek (2.5–25 cm long, @ ~16 trout/100

m); and an unnamed headwater tributary (7.5–15 cm long, @ ~16 trout/100 m). The North Fork

tributary, Indians Creek, did not contain rainbow trout.

Stocking of hatchery-reared salmonids in the San Antonio River has continued over the

years. For example, 2,000 rainbow trout (@ 551/kg) were planted in each of the upper and

lower river on 7 June 1980.

Although the availability of steelhead spawning and rearing habitat was very limited in

the lower San Antonio River even before dam construction (see above), the CDFG still identified

steelhead as inhabitants of the San Antonio below the reservoir as of 1981 (R. Benthin, CDFG,

unpubl. letter of 4 March 1981). Presumably, it was assumed that steelhead still entered the

lower river from the Salinas when runoff was sufficient to provide a continuous migration

corridor. However, lack of access to historic spawning and rearing habitats in the perennial

headwaters greatly limits steelhead use of the San Antonio River.

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Santa Margarita Creek and Tributaries

Juvenile steelhead/rainbow trout were abundant in Santa Margarita Creek when

surveyed by Barclay (1975).

Juvenile steelhead/rainbow trout were present in the perennial Santa Margarita Creek

tributary, Tassajara Creek, when surveyed by the CDFG during the mid-1930’s. A lack of

suitable spawning areas may have been a limiting factor for steelhead production. As of 1951, a

few steelhead still entered Tassajara Creek when stream flow was sufficient (W. A. Evans,

CDFG, unpubl. field notes of 5 April 1951). Juvenile steelhead/rainbow trout were abundant in

Tassajara Creek when surveyed by Barclay (1975).

The Tassajara Creek steelhead population was supplemented with 10,000 juveniles in

1932, 8,000 in 1933, and 5,000 (@ 1,728/kg) from the Brookdale Hatchery on 29 June 1938.

Juvenile steelhead were present in the perennial Santa Margarita Creek tributary, Trout

Creek, when surveyed by the CDFG during the mid-1930’s. Spawning areas were common in

the lower portion of the 6.4 km long stream, and scattered in the upper portion. No diversions or

migration barriers were observed. Trout Creek was apparently regarded by local anglers as one

of the best trout streams in San Luis Obispo County, although the surveyer thought that steelhead

production was limited by a lack of flow and heavy fishing pressure.

Early CDFG stocking records showed that the Trout Creek steelhead population was

supplemented with plants of 16,000 juveniles in 1933, and 5,000 (@ 1,728/kg) from the

Brookdale Hatchery on 29 June 1938. Some 4,000 hatchery-reared rainbow trout were planted

in 1932, and a total of 21,000 brown trout during 1932–1936.

Salmon Creek Drainage Salmon Creek is the southernmost steelhead stream in Monterey County. It is a very

high gradient creek in which a 30 m high waterfall, about 1.6 km upstream from the mouth,

marks the upper limit for steelhead access (CDFG, unpubl. field note of 7 February 1961). The

CDFG surveyed the lowermost 5.6 km of Salmon Creek during 3–4 August 1961. The

approximate stream flow under late-summer conditions was strikingly low: the average at two

stations in the upper creek was about 0.6 L/s. Spawning habitat in the lower creek for steelhead

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was very limited; the availability for resident rainbow trout above the barrier falls was generally

greater. Despite the exceptionally low flow conditions, summer rearing habitat for juvenile

steelhead/rainbow trout was apparently adequate as the high stream gradient and bedrock

substrate resulted in the formation of many pools with boulder cover. There was only one small

diversion of water, from the upper creek to the Salmon Creek Ranger Station. There were two

partial bedrock barriers to steelhead migration below the falls, and both partial and complete

barriers to resident rainbow trout movement above the falls. Rainbow trout in the upper creek

were mostly about 2.5–15.0 cm in length (mean ≈ 5.0 cm), and occurred at a high visually-

estimated density in one reach of about 230 trout/100 m. In the lower creek, juvenile

steelhead/rainbow trout were 2.5–15.0 cm in length (mostly 5.0–10.0 cm) and the visually-

estimated density from one pool count was about 178 trout/100 m. Fishing pressure was heavy

in the lower creek during the beginning of the trout season in spring.

Salmon Creek was included in the CDFG’s attempt to develop brown trout fisheries in

Monterey County during the 1950’s and 1960’s. On 9 May 1962, 6,000 brown trout fingerlings

were planted in the upper creek near the Spruce Creek Camp (CDFG, unpubl. field note of 9

May 1962). Conditions for trout were generally favorable as described in the 1961 CDFG

survey, and many 10–15 cm long rainbow trout were observed. Another 600 brown trout

fingerlings were planted in upper Salmon Creek on 23 June 1963. Neither of these plants was

evaluated for their success, although brown trout survival in nearby streams was very low (M. L.

Johnson, CDFG, unpubl. memo. of 14 October 1963).

Salmon Creek, along with Alder, Mill, Plaskett, and Prewitt creeks, is particularly

interesting in that it seems to represent the lower dimensional threshold for drainages that can be

utilized by steelhead along the steep Big Sur Coast.

San Jose Creek Drainage San Jose Creek was surveyed by the CDFG in July–August 1962, from the mouth to the

creek source, for a distance of about 13 km. A 2.4 m bedrock waterfall formed a partial

migration barrier to steelhead, about 2.4 km from the mouth. In addition, a complete barrier was

formed by a 6–7.5 m high earthfill dam, located another 2.4 km above the waterfall. Much of the

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stream bottom consisted of sand, but there were scattered beds of suitable spawning gravels for

steelhead below the dam, and for resident rainbow trout above the dam. Rearing habitat for

juvenile steelhead was adequate. Two small diversions were noted. The local warden estimated

the annual run of adult steelhead at 50–100 fish. Resident rainbow trout densities were very low

in the 8 km of stream above the dam; only two 12.5–15 cm fish were seen. In the 2.4 km section

between the dam and waterfall, the density of 5–18 cm trout was about 30 fish/km. O. mykiss

density was highest in the 1.6 km of flowing stream below the waterfall, where there were about

110 fish/km, 5–15 cm in length. O. mykiss in the middle and lower sections averaged 5–10 cm

in length. In summary, reproduction and juvenile recruitment were successful in the creek

sections accessible to steelhead. The low density of resident rainbow trout in the section above

the dam was attributed to two successive years of nearly complete desiccation in that portion of

the stream. These observations were in stark contrast to a 1961 CDFG document which stated

that San Jose Creek was “of little use to fishlife” with regard to a proposed highway bridge

replacement project (R. L. Jones, CDFG, unpubl. interdep. comm. of 29 June 1961).

In September 1962, the CDFG also made observations of several tributaries to San Jose

Creek, and the following conclusions were made. Seneca Creek, Van Winkler Creek, and

several small unnamed tributaries were judged to have low potential for O. mykiss production

due to their steep gradient and intermittent flow. The North Fork San Jose Creek reportedly had

limited salmonid production potential. Observations were also made of Williams Canyon Creek,

the report of which is included below.

When San Jose Creek was surveyed again by the CDFG in May 1963, siltation of the

stream bottom had intensified due to runoff from heavy winter and spring storms. The quality

and quantity of both spawning and rearing habitat were reduced. No fish were observed above

the waterfall, although several 15 cm juvenile steelhead were seen attempting to pass the falls.

As of August 1979, the earthfill dam had been temporarily removed to extract

accumulated sediment. The damsite was now passable to steelhead and juveniles were observed

in pools upstream from that point. San Jose Creek has apparently not been surveyed in recent

years. However, in the report of a 1990 survey of Williams Canyon Creek (see below), it was

mentioned that the creek had not reached the ocean during the drought that had begun in water

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year 1986-87, thus precluding steelhead migrations to and from the Pacific Ocean.

Williams Canyon Creek

When observed by the CDFG in September 1962, Williams Canyon Creek had perennial

flow, and although none was seen during this survey, the local warden reported trout to 1.6 km

above the mouth. The stream had limited spawning gravels and was heavily silted due to

logging activities prior to 1900.

The CDFG surveyed Williams Canyon Creek in February and April 1990, from the

confluence with San Jose Creek to the headwaters (F. Roddy, CDFG, unpubl. memo. of 30 April

1990). Generally, the creek was heavily silted, and consequently, no suitable spawning areas

were observed. Pools were also filled in with sand. In a single 46 m reach in the lower creek,

only two O. mykiss were captured by electrofishing. Lengths and weights were 149 and 170 mm

FL, and 40 g and 60 g, respectively. Several partial and complete migration barriers were

identified, created by logjams and culverts. In addition to siltation, the observed low abundance

of O. mykiss was attributed to several successive years of drought. It was noted that, during the

drought, San Jose Creek had not reached the ocean, thus precluding both adult and juvenile

steelhead migrations.

Soberanes Creek Drainage The very small yet perennial Soberanes Creek has not been accessible to steelhead within

recent geological history due to a 2.4 m waterfall at the mouth. The stream may also be

unsuitable habitat for resident rainbow trout, as none was found when the lowermost 3.2 km of

the creek were spot-sampled with a dip net and electrofisher on 4 April 1989 (Rischbieter

1990b).

Soda Springs Creek Drainage The lowermost 1.6 km of Soda Springs Creek were surveyed by the U.S. Forest Service

on 17 September 1981. The creek was described as a very small, rocky, high gradient stream

with poor riffle and pool development and little summer flow (~1.5 L/s during this survey).

There was a 3 m fall just above the Highway 1 crossing which created a complete barrier for

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upstream migrating steelhead. No fishes were present in the stream and, overall, Soda Springs

Creek may simply be too small for steelhead use.

Vicente Creek Drainage The CDFG surveyed lower Vicente Creek on 7 September 1961. The stream was

described as small and rugged. The creek had evidently not been populated by steelhead within

recent geological history, because of an impassable bedrock fall near the mouth. However,

resident rainbow trout were observed in pools beneath the Highway 1 bridge. A local resident

reported that the trout population in the creek was small, and that the fish caught were seldom

>15 cm in length. The stream was privately owned and closed to public access.

Villa Creek Drainage Villa Creek is a small, rocky, high gradient stream that has evidently not been populated

by steelhead within recent geological history. A CDFG survey of the lowermost 5.6 km of the

creek on 4 August 1961 revealed the presence of a series of bedrock and logjam barriers,

beginning near the mouth, which blocked steelhead access. No fish were seen in the lowermost

third of the creek, nor in the extreme headwaters. The mid-portion of the stream was populated

by resident rainbow trout, 5.0 –15.0 cm in length, at a visually-estimated density of about 230

trout/100 m. Spawning areas were very limited, but rearing habitat in the form of pools and

cover seemed adequate. The survey report indicated that local residents had stocked the creek,

presumably with rainbow trout, about 1900. Being undocumented otherwise, the reliability of

this stocking record is unclear.

On 11 August 1969, the CDFG rechecked lower Villa Creek for steelhead access (CDFG,

unpubl. field note of 21 August 1969). There was a natural boulder barrier about 90 m above the

mouth that was deemed impassable by adult steelhead under high winter flow conditions. No

fish were seen in the lowermost 180 m of the creek, although rainbow trout up to 18 cm long

were seen at a low density above this reach.

The U.S. Forest Service surveyed the lowermost 2.4 km of the creek on 19 September

1981 and reaffirmed the presence of the 6 m high boulder barrier, about 90 m above the mouth,

which blocked adult steelhead immigration. Overall, the character and condition of the creek

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seemed unchanged since the 1961 CDFG survey. The creek was morphologically stable through

most of the survey area. Resident rainbow trout were common in abundance, and visual density

estimates averaged 39 trout/100 m in the lower survey area, and about 49 trout/100 m in the

upper survey area. Corresponding mean lengths were 14.6 cm and 16.0 cm (overall range, 2.5–

25 cm).

Wildcat Creek Drainage Wildcat Creek apparently has too high a gradient to provide access or habitat otherwise

for steelhead or resident rainbow trout. This conclusion is based on the results of a CDFG

reconnaissance of the stream in 1981 (as cited in Rischbieter 1990b).

Wild Cattle Creek Drainage Wild Cattle Creek has apparently not been used extensively by steelhead, if at all, within

recent geological history. The USFS surveyed the lowermost 800 m of the creek on 13 July

1981 and found that a 2.4 m boulder barrier would limit steelhead access to a point about 90 m

above the Highway 1 crossing. No fish were seen below or above the barrier. Overall, the creek

was deemed too steep, with too little pool development to support rainbow trout much less

provide spawning and rearing habitat for steelhead. Rainbow trout presence/absence was not

evaluated above the survey area where the stream ran through private property.

Willow Creek Drainage Historically, Willow Creek was one of the most productive steelhead streams in

southernmost Monterey County. Longtime visitors to the creek reported seeing adult steelhead

in groups of 10–12 during most years, although none had been observed by early February of the

1960–1961 spawning season when low flow conditions prevailed (CDFG, unpubl. field note of 7

February 1961).

On 14 June 1961, the CDFG surveyed a 1.6 km reach of Willow Creek, near the

confluence with the North Fork Willow Creek. Spawning gravel for steelhead was scarce in the

survey reach, but rearing habitat in the form of pools and cover was abundant. Small diversions

removed water from the stream for domestic use by local miners. Juvenile steelhead/rainbow

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trout occurred at a visually-estimated density of about 246 trout/100 m. The trout were about

7.5–25.0 cm long, although most were <13 cm. A part-time local resident since 1927 reported

that steelhead used the drainage to about 5 km above the main stem/north fork confluence. He

also reported that summer angling pressure had increased over the years and that few catchable-

size trout remained in the stream after the early fishing season.

The CDFG surveyed the entire creek for a distance of about 18 km during 25 July–3

August 1961. Like the other streams in the area, Willow Creek was characteristically small, had

a low summer flow and a high gradient, especially in the headwaters. Two small diversions

were noted. The stream substrate was dominated by cobble, boulders, and bedrock. Suitable

gravel for steelhead spawning occurred throughout the stream but in small quantities. The best

spawning areas were in the upper half of the drainage, although their use by steelhead was

limited because of bedrock and logjam barriers above the main stem/north fork confluence.

Rearing habitat in the form of pools and cover was abundant throughout the stream. Visually-

estimated densities of juvenile steelhead/rainbow trout ranged from 98 to 246 trout/100 m from

upper to lower Willow Creek, and about 62 trout/100 m in the north fork. Annual steelhead runs

had reportedly been well below normal during the previous 3 yr with low rainfall.

When surveyed by the USFS during 26–27 September 1981, the stream had apparently

degraded somewhat from 20 yr earlier because of siltation from mining in and near the creek

which resulted in pool filling. Numerous debris dams in the middle and upper stream were also

causing erosion and migration barriers. The likely sources of woody debris were mining activity

near the stream and the Los Burros fire of 1970. Water quality was reduced from the input of

organics, possibly sewage. Yet, production of steelhead/rainbow trout and their invertebrate

food items was still rated relatively highly. Visually-estimated densities in the lower, middle,

and upper survey reaches were 49, 66, and 82 trout/100 m, respectively. The overall size range

of trout was 2.5–30.5 cm, and the mean in each reach was about 13 cm. The largest individuals

occurred in the mid- to upper stream.

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The stream was surveyed again by the CDFG, from the mouth to its headwater

tributaries, in August 1973. The overall condition of the stream was apparently about the same

as in 1960, although water extraction had increased due to the presence of two diversion weirs

(inoperative at the time of the survey) and three wells in the system. Juvenile steelhead were

observed throughout the drainage, except above impassable waterall barriers on Burnett Creek

and its tributary, Spanish Cabin Creek. Aside from a high abundance of young-of-the-year in

Green Canyon Creek, densities of young steelhead in the other tributaries were judged to be low,

relative to the amount of available habitat. All juvenile steelhead found in the upper Arroyo de

SAN LUIS OBISPO COUNTY

Arroyo de la Cruz Drainage The main stem Arroyo de la Cruz is formed by the confluence of two main headwater

streams, Burnett and Marmolejo creeks. Burnett Creek is typically regarded as the headwater

extension of the main stem, and is treated so here. The relatively small body of information on

other tributaries is also included within this account on the main stem.

The Arroyo de la Cruz drainage lies on property owned by the Hearst Corporation, which

limits access to the stream. CDFG observations beginning in 1937 described the intermittency of

flow in the lower stream, but the persistence of the lagoon. Such observations were made both in

summer and winter. Although records were not present, the steelhead population was evidently

supplemented with juvenile plants made in the lagoon.

The CDFG surveyed the Arroyo de la Cruz on 14 January 1960. Spawning areas were

abundant in the lowermost 11 km of the stream, but scarcer above this point toward the

headwaters. Rearing habitat was adequate throughout, but of highest quality in the upper stream

area. No permanent diversions or barriers were noted. Cattle grazing caused streambank erosion

in the lowermost 11 km of stream, but siltation was not extreme. No fish were seen in the stream

during this survey, but they were when the CDFG made another brief survey on 29 June 1960.

Juvenile steelhead, 5–10 cm long, occurred in approximate densities of 50–100 fish/pool. The

Arroyo de la Cruz tributary, Green Canyon Creek, also contained 25–50 juvenile steelhead (4–

7.5 cm long) per pool during this survey. A silt-filled 3 m high dam with a dysfunctional fish

ladder was located about 8.4 km upstream from the confluence with Green Canyon Creek.

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la Cruz, Burnett Creek, Spanish Cabin Creek, and Marmolejo Creek were covered with black

spots thought to be encysted metacercaria of the monogenetic trematode, Neascus, such as those

found on steelhead in San Carpojo Creek. Juvenile steelhead in Green Canyon Creek did not

have the “black spot disease”.

The Arroyo de la Cruz was surveyed during September–October 1978 (G. J. Stone,

unpubl. file report to the CDFG). Stream condition was similar to that in 1973. Juvenile

steelhead were captured both with hook-and-line and by electrofishing. The lagoon supported a

large number of steelhead, which were silvery and 15–20 cm long. From SKM 10.5 through 20

in Burnett Creek, trout as large as 35.6 cm were caught in large pools. About 75% of all

steelhead observed were infected to varying degrees by the black spot disease. Observations

made in the upper Arroyo de la Cruz and tributaries suggested that juvenile abundance was about

33 trout/100 m.

During 17 August–22 October 1978, Knable (1978) estimated juvenile steelhead

abundance and biomass in the Arroyo de la Cruz and five other San Luis Obispo County coastal

streams. The Arroyo de la Cruz was selected to represent a steelhead production system

approximating pristine conditions. Abundance and biomass were estimated using electrofishing

and the two-pass removal method in six randomly-selected, 30.5 m long sections, in three 1.6 km

long stream reaches. Most of the stream was dry below SKM 11.

Mean estimated juvenile density was 13 ± 15 trout/100 m (range, 0–46 trout/100 m).

Estimates of population on a kilometer basis increased from downstream (70 trout in SKM 6.4–

8.0) to upstream (439 trout in SKM 16.1–17.7). Many juvenile steelhead were also seen in the

large lagoon and in large pools in SKM 17.7–19.3, but no abundance estimates were made at

these locations. Apparently, juvenile recruitment in 1978 was poor as only 2% of sampled trout

(n = 52) were likely young-of-the-year (50 –99 mm in length), 54% were 100–149 mm, and 44%

were 150–199 mm. Most sampled trout were yearlings as average individual mass was 29 g.

Knable (1978) concluded that the Arroyo de la Cruz drainage remained basically

unaltered, relative to the other creeks in his survey. Exceptions were conversion of the riparian

corridor to grazing land to within 9 m of the stream, and fecal pollution from livestock.

In November 1978, the Hearst Corporation applied to the California State Water

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Resources Control Board for a permit to pump water from the Arroyo de la Cruz. The CDFG

and Jones & Stokes Associates conducted a cooperative study during August–October 1981 to

collect baseline data on the life history and population size and structure of steelhead in the

stream. The forthcoming synopsis of the results of this study are based on Jones & Stokes

Associates and California Department of Fish and Game (1982) and data contained in the CDFG

file (P. Chappell, CDFG, unpubl. data).

On 19 August 1981, 111 juvenile steelhead were captured in the Arroyo de la Cruz

lagoon by electrofishing and hook-and-line. The steelhead had a mean (± SD) length of 15.3 ±

1.6 cm FL (range, 10.5–20.0 cm FL; Fig. 16) and were primarily age 1+. There was no

significant difference in steelhead fork lengths among capture methods (t = –0.26, p = 0.80).

The lagoon was isolated at this time, due to a lack of freshwater inflow and a sandbar which

closed the mouth of the stream. One hundred of the captured fish were marked and released for

future recapture and estimation of abundance. The lagoon population was sampled again by

hook-and-line during 25–27 August 1981. Of 100 steelhead, only one was a recapture and the

abundance estimate for the lagoon was 5,100 fish; confidence limits could not be calculated

because of the extremely low recapture rate.

The second phase of this study was conducted during 20–22 October 1981 when two

reaches of Burnett Creek were sampled by use of electrofishing to estimate juvenile steelhead

abundances. Stream flow was continuous in Burnett Creek from the Van Gordon Creek

confluence, to about 0.8 km below the Marmolejo Creek confluence in the main stem Arroyo de

la Cruz. There was interrupted flow upstream and downstream from these points, respectively,

although the main stem was completely dry downstream from the confluence with Long Canyon.

The estimated density of juvenile steelhead in a 30.5 m reach about 0.4 km above the Van

Gordon Creek confluence was 249 fish/100 m (95% C.L., 171–328 fish/100 m). In a 38 m reach

about 0.8 km above the confluence with Spanish Cabin Creek, estimated density was nearly

identical: 241 fish/100 m (194–289 fish/100 m). The fish averaged 7.1 ± 2.8 cm FL (range, 3.5–

20.5 cm FL; n = 140), and 92% of the combined sample comprised age 0+ fish; 7% were age 1+

and 1% was age 2+. The black spot disease was prevalent among captured fish, and some

individuals were smolting. The Arroyo de la Cruz was characterized by large bedrock pools

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where young-of-the-year steelhead were abundant. High concentrations of young steelhead in

isolated pools were found as far upstream in the system as Burnett Creek near Burnett Camp.

This stream area lacked a riparian understory, and stream banks were eroded due to heavy

grazing pressure.

A complementary analysis was conducted to determine if there was a difference in size-

at-age between lagoon-dwelling steelhead and those sampled from the perennial stream reach, as

described above (W. M. Snider, CDFG, unpubl. memo. of 6 January 1982). One could predict

that lagoon-rearing steelhead would have higher growth rates than creek-rearing steelhead.

However, there was no significant difference (t = –0.55, p = 0.59) in average (± SD)

backcalculated fork length at age 1 between lagoon-dwelling (89.4 ± 11.7 cm FL, n = 43) and

stream-dwelling (91.9 ± 14.9 cm FL, n = 9) steelhead from the 1980 year-class; there were too

few fish from the 1979 year-class to be statistically analyzed. This result indicated that all age

1+ steelhead had reared under similar conditions in the stream portion of the system through

their first year of growth. Steelhead found in the lagoon apparently migrated downstream during

their second year. It was concluded that the creek was used for spawning and as a young-of-the-

year nursery, while the lagoon functioned primarily as a rearing area for ≥ 1+ steelhead.

The Hearst Ranch diversion was eventually approved with stipulations for a fish passage

structure at the weir.

During the 1983-84 steelhead season, the Santa Lucia Flyfishing Club conducted a creel

census of four San Luis Obispo County coastal streams, including the Arroyo de la Cruz (Santa

Lucia Flyfishing Club, San Luis Obispo, newsletter of April 1984). Surveys occurred on 20 of

the 50 legal fishing days, during which 83 anglers were interviewed and 112 steelhead were

reportedly landed as a result of 239.25 hr of angling. Of these fish, 111 were juveniles ≤ 20 cm

in length. One adult steelhead was taken on 15 January 1984 which measured 74 cm in length.

Several other adult steelhead were observed in the stream throughout January, and one was seen

on 22 March 1984 which was trapped in the creek as a sandbar had closed the mouth by 25

January 1984.

Jones & Stokes Associates (1986) collected additional baseline data on the Arroyo de la

Cruz steelhead population in 1985. Juvenile steelhead abundance estimates were made by use of

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electrofishing and the three-pass removal method. One 30.5 m riffle in each of upper and lower

Burnett Creek, and in the upper main stem Arroyo de la Cruz, was sampled in July and October.

Abundance estimates (± SD) averaged 289 ± 98 trout/100 m in July, but when the same riffles

were sampled again in October, abundances had decreased by an average of 55% when mean

estimated abundance was 129 ± 46 trout/100 m. Similarly, juvenile steelhead abundances,

determined by direct enumeration (snorkeling) in one shallow pool in each of upper and lower

Burnett Creek, ranged from about 230–525 fish/100 m in July, and decreased to an average (±

SD) observed abundance of 167 ± 69 fish/100 m in October. These losses may have been due in

part to a reduction in both quantity and quality of habitat as stream flow decreased. The

estimated abundance of juvenile steelhead in the lagoon in October was 424 fish, as determined

by combined snorkeling and electrofishing counts. Juvenile population structure and distribution

of age-classes were similar to those found in the 1981 survey. The population segment in

Burnett Creek and the upper Arroyo de la Cruz was highly dominated by age 0+ steelhead. The

mean length of these fish only increased from 55.1 mm FL in July to 61.3 mm FL in October,

which was probably the result of not only poor growth as indicated by the authors, but perhaps

also size-selective mortality and/or dispersal. Only 10–15 age ≥ 1+ trout, about 150–300 mm in

length, were observed in the October creek samples, thus comprising a small proportion of the

juvenile population in the stream portion of the system. Lagoon-dwelling steelhead in October

ranged from about 120–250 mm FL. Age 1+ fish dominated in number and the mode in the

length-frequency distribution was between 150 and 160 mm FL. There was a relatively small

proportion of age 2+ and 3+ fish and young-of-the-year were absent. Nineteen of the 24 trout

(79%) in the lagoon had morphological characteristics of smolts (absence of parr marks, silvery

coloration, reduced condition factor); the mean condition factor (105[weight, g]/[fork length,

mm]3) of smolt-like steelhead (1.16) was lower than that of all steelhead in the lagoon (1.33).

As in earlier surveys, the black spot disease was prevalent among juvenile steelhead in the

stream portion of the system, but <20% of lagoon-dwelling steelhead were infested with the

parasite. Two adult steelhead were observed which had been trapped in fresh water since the

previous spawning season: one in the lagoon estimated at about 4 kg; and one in upper Burnett

Creek, a male which measured 635 mm FL and 2.2 kg. The skeleton of a third adult was found

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in Burnett Creek; the size of this fish was estimated at 510 mm, based on skeletal length.

Interrupted surficial flow in the lower Arroyo de la Cruz separated the perennial stream from the

lagoon typically for 3–5 months each year, depending on interannual differences in precipitation.

The conclusions of this study were essentially the same as those of Snider, above: (i) the

perennial stream was used for spawning and first year rearing of steelhead; and (ii) age 1

steelhead migrated downstream where possibly some smolted and continued to the ocean, while

others reared for one or more years in the lagoon before emigrating to salt water.

In 1993, the CDFG assessed the stream habitat and associated steelhead population in the

Arroyo de la Cruz (Nelson 1994d). This suite of studies consisted of stream surveys, emigrant

trapping, and electrofishing surveys. Stream survey results are highlighted here first to provide

an overview of the study area.

The main stem was surveyed on 6 July 1993 from the lagoon to the confluence of Burnett

and Marmolejo creeks for a distance of 18 km. The lowermost 15.6 km were dry except for

isolated bedrock and boulder-scour pools. There was perennial flow in the uppermost 2.4 km,

and the lagoon was full. The channel in the low-gradient dry section was relatively broad with

denuded, eroding stream banks. These conditions were associated with cattle grazing and

numerous road crossings, primarily in the lower 8–10 km of stream. The perennial reach had a

moderate gradient and more confined channel stabilized with riparian vegetation. Spawning

areas were abundant. Most of the habitat was pools and step-runs with sufficient cover to

provide perennial rearing habitat for juvenile steelhead. Age 0+, 1+, and ≥ 2+ steelhead were

seen in isolated pools in the dry reach and throughout the perennial reach.

Burnett Creek was surveyed on 7 April 1993 from the Marmolejo Creek confluence to

Spanish Cabin Creek for a distance of about 2.4 km. With regard to gradient, channel and

streambank stability, Burnett Creek was basically a continuation of the mainstem perennial reach

as described above. There were numerous small spawning areas, and an abundance of pools and

runs with cover provided rearing habitat. The silt-filled weir with inadequate fish ladder seen in

earlier surveys was still present. Apparently, the weir was only a partial barrier as age 0+ and 1+

steelhead were seen throughout the reach.

The lowermost 1.8 km of Marmolejo Creek were surveyed on 17 August 1993. About

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0.64 km above the mouth, a series of boulders created a likely barrier to immigrating adult

steelhead. Otherwise, the general character of the lower 1.1 km was much the same as at Burnett

Creek, with regard to gradient, channel confinement, riparian canopy, and the presence of

spawning and rearing habitats. Above the point, the channel was broad, riparian canopy was

lacking, and flow was subsurface, perhaps the result of cattle grazing. There was surficial flow

further upstream but this area was not surveyed extensively. Age 0+ through 2+

steelhead/rainbow trout were seen above and below the boulder series, and above the dry reach.

Overall, conditions in the drainage seemed little changed from earlier surveys, with the

negative impacts of cattle grazing on stream habitat persisting.

Nelson (1994d) fished a downstream migrant trap on the main stem at SKM 1.1 from 5

April 1993 to 5 June 1993. During nine weeks of trapping, 44 steelhead parr, 24 partial smolts,

134 smolts, 11 rainbow trout, and 1 post-spawning adult were captured. Parr averaged 71.2 mm

TL (range, 35–120 mm TL) and were thus dominated by age 0+ fish, while partial smolts,

smolts, and rainbow trout averaged 180.0 mm TL (range, 105–335 mm TL) and were dominated

by age 1+ and 2+ fish. The adult steelhead was 491 mm TL. About 75% of smolts were

captured during the first two weeks of trapping, which indicated that many smolts emigrated

prior to 5 april 1993.

Nelson (1994d) estimated the abundance of juvenile steelhead in the perennial reach of

the Arroyo de la Cruz during 18–19 October 1993, using electrofishing and the multiple-pass

removal method. The estimated abundance from composite catches in three 91 m long sections

was 185 trout, or 67 trout/100 m. The expanded estimate for the 3.2 km perennial reach was

2,165 trout. The captured trout were 56–269 mm TL, but the catch was dominated by young-of-

the-year 50–100 mm TL (54%) and yearlings 100–150 mm TL (36%).

Nelson (1994d) continued upstream with abundance estimates in two 91 m long sections

in Burnett Creek. The estimated abundance from composite catches was 157 trout, or 86

trout/100 m. The expanded estimate for the 2.7 km perennial reach was 2,334 trout. The

captured trout were 56–244 mm TL, but again the catch was dominated by young-of-the-year

50–100 mm TL (49%) and yearlings 100–150 mm TL (32%).

Marmolejo Creek only had 81 m of live stream, all of which was sampled. Nelson

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(1994d) estimated abundance in this reach at 116 trout, or 144 trout/100 m. The captured trout

were 53–224 mm TL, and highly dominated by young-of-the-year 50–100 mm TL (82%).

Nelson (1994d) concluded that the Arroyo de la Cruz provided an abundance of

spawning habitat, but that high quality rearing habitat was limited because of interrupted flow

conditions. She recommended that the Arroyo de la Cruz be protected as a steelhead production

system by maintaining the perennial stream reaches and the lagoon. Removing the silt-filled

weir on Burnett Creek would enhance stream channel function and steelhead access to the

uppermost drainage. Further enhancement would be gained by increasing wetted stream length

in reaches used by steelhead. Sedimentation from cattle grazing in the upper drainage was

regarded as a negative impact needing attention.

Results from Knable (1978), Jones & Stokes Associates and California Department of

Fish and Game (1982), Jones & Stokes Associates (1986), and Nelson (1994d) demonstrate the

temporal variation in juvenile steelhead densities and age structure in the perennial reach of the

Arroyo de la Cruz and Burnett Creek. Juvenile densities averaged 27 ± 10 trout/100 m in early

fall 1978, 245 ± 6 trout/100 m in October 1981, 129 ± 45 trout/100 m in October 1985, and 76

± 13 trout/100 m in October 1993. Most captured steelhead were yearlings in 1978, young-of-

the-year in 1981 and 1985, and there was a relatively high proportion of yearling and older fish

in 1993. Low densities of proportionately many yearlings observed in 1978 and 1993 may have

reflected the impact of the 1976–77 and 1986–92 droughts on the steelhead population.

Arroyo Grande Creek Drainage The Arroyo Grande Creek drainage area has been developed extensively for agriculture,

and the stream is apparently heavily eutrophicated because of the discharge of nutrient-rich

agricultural wastewater. Among other impacts, water is both diverted from the stream and

pumped from the ground for irrigation. The lowermost portion of the stream, from the city of

Arroyo Grande to the stream mouth, is channelized for flood control.

Historically, the Arroyo Grande system has supported steelhead, and rainbow trout in the

mountainous headwaters (Jordan 1895). A mid-1930’s CDFG survey report in the upper Arroyo

Grande mentioned the presence of both rainbow trout and juvenile steelhead and that fishing

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pressure was heavy. A January 1949 CDFG field note mentioned that steelhead entered the

stream during high flow periods, in May 1950 many young-of-the-year and 5–15 cm juveniles

were observed in the upper stream, and in October 1950 the stream was deemed unsuitable for

rainbow trout stocking because of interrupted flow. Angling for juvenile steelhead, those of

which occurred “by the hundreds” in the stream’s lagoon, was reportedly good in May 1953. In a January 19

Juvenile steelhead were not observed during this survey. No migration barriers were seen.

Fishing was reportedly heavy in both the winter steelhead season and the summer trout season.

In June 1959, a low density of juvenile steelhead was observed in the upper stream above the

confluence with the Arroyo Grande tributary, Lopez Canyon Creek.

The CDFG surveyed the stream again in May 1960. Low densities of rainbow trout and

juvenile steelhead were seen, ranging in length from 5 to 30.5 cm. It was also reported that

catchable rainbow trout were planted regularly each year when flow conditions permitted. The

stream was noted as supporting one of the larger steelhead runs in the south coast region, which

was estimated to be equal in magnitude to those found in Santa Rosa Creek, the Arroyo de la

Cruz, San Simeon Creek, and San Carpojo Creek.

A coarse estimate of the long-term trend in the Arroyo Grande steelhead run was

constructed by the CDFG in 1961 (Table 2), based on interviews of about 50 local landowners

and sportsmen (R. N. Hinton, CDFG, unpubl. file report of 1 March 1961). Apparently,

maximum estimated run size had decreased by a factor of about 50, from 5,000 adults in 1940 to

less than 100 adults in 1960. Several hundred juvenile steelhead had been seen in the creek in

each of the past few years.

A few adult steelhead were eventually seen later in the 1960-61 season. Two were

reportedly taken by anglers on 4 March 1961 in the surf off the mouth of the creek. One of these

fish was 54.5 cm in length and weighed about 1.4 kg. A 61 cm female and 12 smaller (23–25

cm) steelhead were seen in the lower stream in mid-March 1961. Juvenile steelhead/rainbow

trout, 5–18 cm long, were observed on 21 March 1961 within a 3 km reach below the confluence

with Lopez Canyon Creek. Stream flow was interrupted, and the trout were concentrated in

pools. No adults were seen, although about 12 potential redds were located within this reach

which otherwise lacked suitable spawning gravel.

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By the time of a CDFG survey in September 1972, the Arroyo Grande had deteriorated

substantially as a viable steelhead stream. Lopez Dam, constructed at the confluence with Lopez

Canyon Creek during the mid-1960’s (see below), blocked steelhead access to upstream

spawning and rearing areas. Two small diversion dams were also noted in the lower stream.

Numerous diversions had been installed along the stream course and various forms of pollution

were noted. No juvenile steelhead were observed in the stream, but some adult steelhead were

reportedly caught each year by local residents.

The Arroyo Grande was surveyed again in August 1978, from the mouth to Lopez Dam,

an estimated 19 km (G. Stone, CDFG, unpubl. file report of 31 August 1978). The survey

consisted of visual observations and electrofishing. Spawning areas were limited, and siltation

was noted as a problem throughout much of the stream, with sediment depths of 2.5–15 cm.

Rearing habitat, on the other hand, was adequate. Overall, the condition of the stream was

unimproved since the 1972 survey, with the exception that willows were being allowed to grow

back in the channelized lower stream. No juvenile steelhead were seen or captured.

During 17 August–22 October 1978, Knable (1978) estimated juvenile steelhead

abundance and biomass in Arroyo Grande Creek and five other San Luis Obispo County coastal

streams. The Arroyo Grande was selected to represent a steelhead production system having

undergone significant modification. No juvenile steelhead/rainbow trout were seen or captured

by electrofishing in six randomly-selected, 30.5 m long sections, in four 1.6 km long stream

reaches. Knable (1978) viewed the Arroyo Grande as the most severly degraded steelhead

stream in his survey, primarily due to channelization, water diversions, and siltation.

The Arroyo Grande has apparently not been surveyed in recent years, yet the presence of

a viable steelhead resource was mentioned in recent (through 1991) CDFG file documents in

connection with a variety of proposed development projects.

Lopez Canyon Creek and Other Tributaries

According to Jordan (1895), Lopez Canyon Creek was “the best-known trout stream in

San Luis Obispo County”. Several Arroyo Grande Creek tributaries were surveyed by the

CDFG in mid-March 1961. Juvenile steelhead, 10–15 cm in length, occurred in densities of

about 2–5 fish/pool in Lopez Canyon Creek, and in its tributary, Vasquez Creek, at about 1–3

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fish/pool. In contrast, no steelhead were observed in Corbett Canyon and Tar Springs creeks,

although potential spawning substrate was present in Tar Springs which may have supported

some spawning during winters of high precipitation.

Lopez Canyon Creek was fully surveyed by the CDFG on 10 August 1961. Some

excellent spawning areas were observed, although they were limited in the bedrock headwaters.

Rearing habitat was adequate for small juvenile steelhead. No barriers or diversions were seen.

Stream flow became interrupted in the middle and lower portions of the stream. Young

steelhead/rainbow trout, ranging in length from about 5 to 15 cm, occurred in visually-estimated

densities of 26 trout/100 m in the upper section, 384 trout/100 m in the middle section, and 39

trout/100 m in the lower section. Overall, Lopez Canyon Creek was rated highly as a steelhead

production area, with a comparable production potential of Santa Rosa and San Carpojo creeks.

The lowermost 3.2 km of Vasquez Creek was surveyed by the CDFG on 20 December

1961. Nearly all the stream bottom consisted of suitable spawning gravel. There were few pools

and little cover to provide rearing habitat, however. A cement swimming pool with flashboard

dam, built into the creek about 1.2 km above the mouth, created a steelhead migration barrier. A

low density of 5–10 cm long juvenile steelhead was observed, and it was predicted that

recruitment had been low during the past several dry years. There was little or no fishing.

Vasquez Creek was recognized as a fair to good spawning tributary when steelhead were able to

access Lopez Canyon.

The lowermost 1.6 km of Wittenburg Creek, the next Arroyo Grande tributary upstream

from Lopez Canyon, was also checked by the CDFG on 20 December 1960. Stream flow was

very low in this section and dry upstream from there. At least half the stream bottom contained

suitable spawning gravel for steelhead. A local resident of 23 yrs reported that steelhead had not

spawned in the creek since the winter of 1957-58, and “that there used to be lots of (steelhead)

spawning” in the creek.

The lowermost 0.4 km of Vasquez Creek was walked by the CDFG on 22 February 1962

to look for spawning adult steelhead. None was seen, although a local resident reportedly saw

two adults spawning just above the confluence with Lopez Canyon Creek and one spent adult

moving downstream, the previous weekend.

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Early fish stocking records showed that the Lopez Canyon steelhead population was

supplemented with a plant of 10,000 juveniles in 1930, 25,000 in 1932, 24,000 in 1933, and

15,000 (@ 1,587/kg) from Brookdale Hatchery (Santa Cruz County) in 1938. The lower section

of the creek was stocked annually with catchable rainbow trout as of the August 1961 CDFG

survey.

The system was greatly altered when, during the mid-1960’s, Lopez Dam was

constructed on the Arroyo Grande at the confluence with Lopez Canyon Creek. The dam thus

blocked steelhead access to upstream spawning grounds in Lopez Canyon, Vasquez, Wittenburg,

and upper Arroyo Grande creeks . Partial mitigation for this loss was the development of a

catchable rainbow trout fishery in Lopez Reservoir. Juvenile steelhead/rainbow trout, 5–23 cm

long, were observed in Lopez Canyon Creek under low flow conditions in a CDFG

electrofishing survey made during 27–28 August 1968 (CDFG, unpubl. data; E. V. Toffoli,

CDFG, unpubl. memo. of September 1968). In contrast, none was found in the creek in a CDFG

electrofishing survey conducted during 10–12 May 1978 (CDFG, unpubl. data).

Cayucos Creek Drainage Cayucos Creek enters the Pacific Ocean along the north shore of Estero Bay. Four dams

in the drainage were surveyed by the CDFG in January 1962 to determine steelhead passage;

three were deemed impassable. Steelhead were apparently still present in the stream in 1989 (B.

Hunter, CDFG, unpubl. memo. of 28 September 1989), yet historical records on the size and

dynamics of this population are otherwise lacking.

Chorro Creek Drainage Chorro Creek flows from dense chaparral in its headwaters, to a gently rolling grassland

and oak woodland landscape, then through agricultural land until it enters Morro Bay. The dam

at Chorro Reservoir, located about 4 km from the streams’s headwaters, marks the upstream

limit of 19 km of potential steelhead habitat.

The stream was surveyed by the CDFG in March 1958. At that time, there was an

apparent abundance of high quality spawning and rearing habitat. Except for Chorro Dam, no

migration barriers were noted, and no pollution sources were seen. Water was pumped from the

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stream in summer for agricultural irrigation. Flow was intermittent in some sections in the

summer. Steelhead were not observed in Chorro Creek during this survey due to high flow and

turbidity, although anecdotes mentioned in the survey report described observations of ascending

adult steelhead (20–30 counted at one point within 0.5 hr as they proceeded upstream) and

angling for steelhead near the creek mouth.

Some 3,167 catchable rainbow trout were stocked in the stream in 1960. A total of

208,436 catchable rainbow trout were planted in Chorro Reservoir from 1953 to 1968 to support

a put-and-take fishery.

When Chorro Creek was surveyed by the CDFG in May 1973, several pollution sources,

including the discharge of agricultural wastewater and chlorinated, secondarily treated sewage,

were degrading the system. Water quality was apparently impacted and enhanced eutrophication

was noted in the lower stream area. In addition, a number of culverts were noted as potential

migration barriers, especially under low flow conditions, and one pumping diversion was sited.

Local residents reported capturing juvenile steelhead/rainbow trout in both the main stem and

tributaries, and observed spawning steelhead in the creek and its tributaries during the winter of

1973. So, despite habitat degradation, the stream still maintained at least a small run of

steelhead.

Thirteen migration barriers of varying degree, caused mostly by dams and road crossings,

were identified throughout the drainage by the CDFG in 1974 (W. M. Snider, CDFG, unpubl.

file report of November 1974). Four of these barriers were on the main stem of Chorro Creek. It

was concluded that elimination of these barriers would at least triple the available spawning and

nursery area, and, in particular, would allow steelhead access to upstream areas with perennial

flow. Poaching and predation would also be lessened because steelhead would not be

concentrated behind these obstructions.

Western Outdoor News (8 March 1974 with photographic documentation) reported the

catch of a 5.4 kg steelhead from Chorro Creek. Barclay (1975) found juvenile steelhead/rainbow

trout in the creek, and “they were abundant in areas with clean, cool waters that flowed over

gravel or other rock substrate.”

Based on an extrapolation of data from Stenner Creek in the San Luis Obispo Creek

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drainage, the annual run of adult steelhead in Chorro Creek was estimated at 160 fish by the

CDFG in 1976 (J. S. Leiby, CDFG, unpubl. memo. of 22 September 1976).

Since April 1979, up to 5,000 steelhead smolts have been stocked annually into Chorro

Creek as mitigation for the California Department of Correction’s Chorro Creek Dam which is a

steelhead migration barrier. For example, 1,500 Mad River smolts (22/kg) were stocked in 1979,

and 5,000 in 1980.

Dairy Creek

The Chorro Creek tributary, Dairy Creek, was surveyed in its entirety by the CDFG

during 24–27 April 1973. High-quality spawning and rearing habitats appeared to be available

to steelhead. Potential migration barriers may have blocked steelhead access to the headwaters.

Cattle grazing in the watershed were a likely source of organic pollution in the stream. Juvenile

steelhead/rainbow trout, 15–25 cm in length, occurred in low densities at two sampling stations

in the lowermost 3.2 km of the stream. Steelhead juveniles up to 20 cm in length were captured

by use of electrofishing during a CDFG survey in May 1973. A concrete apron at the Highway 1

crossing was identified as a low flow migration barrier by the CDFG in 1974 (W. M. Snider,

CDFG, unpubl. file report of November 1974). In a grant proposal for a steelhead habitat

improvement project, it was mentioned that San Luis Obispo County park personnel had

observed steelhead in Dairy Creek as late as 1987.

San Bernardo Creek

The Chorro Creek tributary, San Bernardo Creek, was surveyed by the CDFG in

February and June 1958, and January 1959 in connection with a proposed dam. Suitable

steelhead spawning and rearing habitat was observed, although only one 13 cm juvenile was

seen in the upper stream area. Algal growth inhibited visibility in the lower stream. Apparently,

rainbow trout in the uppermost portion of the stream supported a small sport fishery. Local

residents reported that adult steelhead entered the stream on two occasions during the winter of

1957-58, each time following an increase in stream flow. Four migration barriers were identified

by the CDFG in 1974 (W. M. Snider, CDFG, unpubl. file report of November 1974). San

Bernado Creek still reportedly supports a steelhead run (T. Tognazzini, CDFG, pers. comm. of

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10 July 1992).

San Luisito Creek

The Chorro Creek tributary, San Luisito Creek, was surveyed by the CDFG on 12 May

1958, in a 3.7 km reach beginning about 1.9 km above the stream mouth. Spawning areas were

rated as excellent, but rearing habitat in the form of pools and cover was lacking in this reach.

Only one water diversion was observed but others were known to exist, and water for diversions

was considered fully appropriated under summer streamflow conditions. No migration barriers

were seen in this reach, but natural barriers were suspected to occur in the high-gradient

headwaters. No pollution sources were identified. Even though no juvenile steelhead were

positively identified during this survey, the stream was described as providing spawning and

rearing habitat for Chorro Creek steelhead.

The CDFG identified two migration barriers on the creek in 1974 (W. M. Snider, CDFG,

unpubl. file report of November 1974). Numerous adult steelhead were reportedly taken by

poachers at the lowermost barrier.

Coon Creek Drainage Coon Creek has apparently never been surveyed by the CDFG. The creek runs through

the southern portion of Montana de Oro State Park. Juvenile steelhead/rainbow trout was the

only fish species found in the creek by Barclay (1975). On 3 April 1986, a 13 cm long juvenile

steelhead/rainbow trout was captured by dipnet about 1.2 km upstream from the mouth (T. L.

Taylor, California Department of Parks and Recreation, unpubl. data). Local state park

personnel have observed both adult and juvenile steelhead in the stream in recent years (R.

Avant, California Department of Parks and Recreation, Montana de Oro State Park, pers. comm.

of 4 May 1993).

Diablo Canyon Creek Drainage Very little is known about the history of steelhead in Diablo Canyon Creek. Juvenile

steelhead/rainbow trout was the only fish species found in the creek by Barclay (1975). With

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construction of the Diablo Canyon Nuclear Power Plant, the lower creek was greatly altered,

including an extensive culvert system. These lower creek alterations probably block steelhead

access to the stream, although resident rainbow trout should still be present in the upper drainage

(W. M. Snider, CDFG, pers. comm. of 11 July 1994).

Islay Creek Drainage Islay Creek lies within Montana de Oro State Park and has been closed to angling since

1968. The lowermost 4.8 km of the creek are available to steelhead, and 9.7 km of the creek

upstream from a migration barrier support a resident rainbow trout population (M. L. Johnson,

CDFG, unpubl. file letter of 24 February 1966). The creek has a very small and shallow lagoon.

In a brief CDFG survey of the stream (M. L. Johnson, CDFG, unpubl. file letter of 1 April

1966), one adult steelhead was observed, and it was concluded that the creek supported only a

small steelhead population. On 13 February 1986, juvenile steelhead were seen at the creek

mouth (T. L. Taylor, California Department of Parks and Recreation, unpubl. data). Local state

park personnel continue to see spawners and high densities of juvenile steelhead in lower Islay

Creek, as well as rainbow trout in the upper drainage (R. Avant, California Department of Parks

and Recreation, Montana de Oro State Park, pers. comm. of 4 May 1993).

Little Pico Creek Drainage No formal record of an historical steelhead run was found for Little Pico Creek. During

the 1983-84 steelhead season, the Santa Lucia Flyfishing Club conducted a creel census of four

San Luis Obispo County coastal streams, including the Little Pico (Santa Lucia Flyfishing Club,

San Luis Obispo, newsletter of April 1984). Surveys occurred on 20 of the 50 legal fishing days.

Two anglers were interviewed who landed no steelhead during 3.00 hr of angling effort.

Reference was made, in several recent (1990) CDFG file documents, to a steelhead

resource and its protection thereof in connection with lagoon alteration. Relative to nearby Pico

Creek, the Little Pico apparently does not have as much deep pool habitat in which juvenile

steelhead may oversummer. However, the dense riparian vegetation along the lower stream does

provide good shelter for trout, and a few juvenile steelhead have been observed in the creek

during snorkeling surveys since May 1992 (M. Jennings, USFWS, pers. comm. of 21 January

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1993).

Morro Creek Drainage A CDFG survey report combining field notes from February 1947 and April 1951 with

observations made in December 1951 stated that steelhead runs in Morro Creek were small and

that they were lightly fished because of limited access to private property in the lower stream

area. Spawning substrate was present in the middle portion of the stream, and natural

propagation was noted to have occurred in the lower mid-section. Upstream migration was

blocked by cascades and a waterfall about 12 km from the mouth. Fishing for resident rainbow

trout in 1951 was reportedly successful (medium to heavy fishing pressure) following a plant of

5,000 catchable-size fish. Some 990 rainbow trout catchables were stocked in 1953 and 1,540 in

1955.

In a January 1962 CDFG survey, the stream habitat was somewhat degraded due to

pollution from an abandoned dump in the lower stream, and because of reduced flow due to

extensive pumping. No migration barriers were observed, except as mentioned above. Drought

conditions had prevailed since 1957-58, thus preventing breaching of the sandbar and adult

steelhead immigration. No steelhead were observed and local residents reported that they had

not seen any in the stream since 1959. Yet, the creek was still regarded as a viable steelhead

production area.

When surveyed again by the CDFG in June 1973, silt was armoring spawning gravel in

the lower stream, but gravel quality was still high in the upper and middle areas. Flow

conditions were improved from 1962 due to increased precipitation, but pollution of various

sorts had apparently increased, including siltation, dumping of garbage, urban and highway

runoff, as well as discharge of agricultural wastewater. Several rainbow trout were captured

above the barrier falls, which averaged 15.7 cm in length (SD = 5.6 cm; n = 15). These fish were

believed to be descendants of catchable rainbows planted in 1953 and 1955. Steelhead juveniles

were seen, but not captured for positive identification, in sections below the falls. Overall, the

steelhead stock may have been negatively impacted by (i) diversion dams lacking optimal

fishways in the lower and middle stream, which would block access to spawning areas, and (ii)

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unstable flow conditions because of water diversions.

Two adult steelhead, about 43 and 58 cm in length, were observed by the CDFG in the

middle portion of the stream on 14 April 1974. On 4 May 1974, two steelhead measuring 30.5–

33.0 cm in length, and one spent female at 51.5 cm FL, were captured by electrofishing in the

same area. No redds were observed.

Barclay (1975) found juvenile steelhead/rainbow trout in Morro Creek, and “they were

abundant in areas with clean, cool waters that flowed over gravel or other rock substrate.”

Morro Creek was surveyed visually and by electrofishing during 1–9 September 1978,

from the mouth through km 19 upstream (G. Stone and R. Adams, CDFG, unpubl. file report).

Suitable spawning gravels were located between stream km 13 and km 18. Gravel beds in the

lower stream were covered with silt. Diversion dams in the lower and middle stream still needed

fishway improvements as noted in the 1973 survey. Two irrigation pumps were seen taking

water directly from the lower creek. The lower and middle creek areas were polluted with urban

debris; agricultural wastewater was identified as a potential pollution source in the lower area.

Small juvenile steelhead/rainbow trout were most common from SKM 11 through SKM 15, and

two trout were captured within each of SKM 1–2 and SKM 6–7. Local residents interviewed

during the survey indicated that Morro Creek had historically supported a productive

steelhead/rainbow trout fishery, but that fishing was no longer worth pursuing there, presumably

because of a greatly reduced population.

During 17 August–22 October 1978, Knable (1978) estimated juvenile steelhead

abundance and biomass in Morro Creek and five other San Luis Obispo County coastal streams.

Morro Creek was selected to represent a steelhead production system having undergone

significant modification. Abundance and biomass were estimated using electrofishing and the

two-pass removal method in six randomly-selected, 30.5 m long sections, in four 1.6 km long

stream reaches. The uppermost stream was dry, in SKM 17.7–19.3.

Mean estimated juvenile density was 14 ± 19 trout/100 m (range, 0–52 trout/100 m).

Estimates of population on a kilometer basis were generally low in the lowermost 8 km (18 trout

in SKM 1.6–83.2) and much higher above SKM 11.3 (average, 343 trout/km). Apparently,

juvenile recruitment in 1978 was fairly low as only 25% of sampled trout (n = 51) were likely

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young-of-the-year (50 –99 mm in length), 43% were 100–149 mm, 25% were 150–199 mm, and

6% were 200–349 mm. Most sampled trout were yearlings as average individual mass was 21 g.

Knable (1978) concluded that lower portions of Morro Creek were evolving toward a

state of advanced degradation. Spawning in the lower creek was compromised by siltation from

adjacent agricultural activities. Pollution from urban debris and reduced flow from water

diversions also decreased habitat quality in the lower creek. Dams at SKM 3.2 and SKM 14.5

still lacked adequate fishways.

The addition of numerous diversions and pumping wells over the years has continued to

deplete the amount of flow in the Morro Creek drainage, although no recent assessment has

apparently been made to ascertain impacts on the steelhead resource.

Little Morro Creek

The Morro Creek tributary, Little Morro Creek, was surveyed by the CDFG in January

1962. It was deemed unsuitable as steelhead habitat because of extremely low and unstable

flow, and a lack of spawning gravel. Local residents reported that they had never seen or heard

of fish in the creek.

Old Creek DrainagePrior to the impoundment of Whale Rock Reservoir in 1961, Old Creek and its tributary,

Cottontail Creek, supported a steelhead run of unknown magnitude. Early CDFG stocking

records indicated that the Old Creek steelhead population was supplemented with 15,000

juveniles in 1932, and 10,000 in 1933. Fingerling steelhead (5–7.5 cm) were common in several

stream sections when surveyed by the CDFG in January 1957. Suitable spawning areas were

present throughout the survey area, including below the proposed dam site. The results of a July

1957 CDFG survey suggested that the run might be relatively small. Juvenile steelhead were

scarce at that time, ranging in length from about 5 to 20 cm, and were observed at a diversion

dam with a dysfunctional fish ladder about 6 km upstream from the mouth. Some fishing for

adult steelhead occurred at the stream mouth in winter.

With completion of the dam at Whale Rock Reservoir, the CDFG placed management

emphasis on the landlocked steelhead in the reservoir system, as only about 1.6 km of Old Creek

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is available to sea-run fish below the dam. The CDFG (1982) conducted studies during the late

1970’s–early 1980’s during which they found that spawning occurred in late winter, and the

juvenile steelhead entered the reservoir from the spawning tributaries mostly at age 1, although

some emigrants were also age 2. It was not indicated if the fish smolted when they entered the

reservoir. Mean backcalculated length at formation of the first annulus was 90 mm FL. Second-

year growth in the reservoir was very good (mean length at annulus 2 = 260 mm FL) but

apparently approached an asymptote beginning in the third year (mean length at annulus 3 = 310

mm FL). No age 4 or older steelhead had been collected from Whale Rock since 1979; the

largest of these fish had exceeded 500 cm FL. The apparent attenuated growth and low survival

of age-3 and older steelhead may have been due to a reduction in suitable forage organisms

(mainly Dipterans and prickly sculpin, Cottus asper), and possibly direct foraging competition

with Sacramento sucker (Catostomus occidentalis), which were introduced to the reservoir

sometime between 1971 and 1978. Some older steelhead also left the reservoir via the spillway,

although the dam spilled infrequently during the study period.

The CDFG (1982) found that about 4 km of high quality spawning and rearing habitat

was accessible to steelhead in Old Creek between the reservoir and a natural barrier. About

another 5 km of potential habitat existed above the barrier. Only about 1.6 km of Cottontail

Creek was accessible to steelhead spawners because of barriers, and, otherwise, the creek

comprised poor quality spawning and rearing habitat because of the effects of agricultural

development, including depleted riparian vegetation from grazing, siltation, and water diversion.

Whale Rock Reservoir has not been stocked with exotic rainbow trout; supplementation

plants have only been made with progeny of Whale Rock broodstock. The landlocked steelhead

in Whale Rock Reservoir may serve as a broodstock for use in stock enhancement efforts in

other San Luis Obispo County stream systems as well (K. R. Anderson, CDFG, pers. comm. of 9

July 1992). It is not known if adult steelhead still enter Old Creek below the reservoir.

Pico Creek Drainage Pico Creek is comprised of its north fork and south fork which converge to form the main

stem about 2.4 km upstream from the mouth. In a CDFG survey in January 1960, suitable

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spawning and rearing habitats were observed, the former especially in the south fork, but no

steelhead were seen. Migration barriers were not present, except possibly one in the upper north

fork. Grazing was noted as heavy in the drainage which may have resulted in some siltation in

the stream due to erosion. A local resident reported that the main stem and portions of the south

fork were dry in summer, leaving the north fork as the most reliable steelhead producing portion

of the stream. This source had also counted between 50 and 100 adults on occasion in a single

pool in spring. A local CDFG warden estimated the size of the run to be about 3,000 adult

steelhead.

On 25 January 1974, a 64 cm adult steelhead was observed in Pico Creek, about 2.4 km

upstream from Highway 1. According to a local resident, only one other adult had been seen

earlier that season, and that more fish were expected in the stream at that time of year (CDFG,

unpubl. field notes). Western Outdoor News (6 August 1976 with photographic documentation)

reported the catch of three 3.6 kg steelhead from Pico Creek.

During the 1983-84 steelhead season, the Santa Lucia Flyfishing Club conducted a creel

census of four San Luis Obispo County coastal streams, including Pico Creek (Santa Lucia

Flyfishing Club, San Luis Obispo, newsletter of April 1984). Surveys occurred on 20 of the 50

legal fishing days. Nine anglers were interviewed who landed no steelhead during 7.75 hr of

angling effort, although there were rumors of steelhead being taken.

Pico Creek continued to be a popular steelhead fishing location. Adult steelhead were

seen entering the lagoon during the late 1980s – early 1990s (K. Worcester, CDFG, pers. obs.),

although no steelhead were seen in the stream during a survey on 12–13 June 1989 (Par

Environmental Services, Inc. 1991). The 1987–92 drought undoubtedly had a significant

negative impact on the small Pico Creek steelhead stock. From May 1992, however, juvenile

steelhead were observed during monthly snorkeling surveys in the lagoon and lowermost 200 m

or so of the creek (M. Jennings, USFWS, pers. comm. of 21 January 1993).

Pismo Creek Drainage Pismo Creek discharges into the Pacific Ocean at Pismo Beach after flowing about 8.5

km through Price Canyon. Its headwater tributaries, East and West Corral de Piedra creeks,

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converge near the community of Edna to form the main stem. When Pismo Creek was surveyed

by the CDFG in September 1972, spawning gravel was present but not very abundant. No

juvenile steelhead or any other fishes were observed from the mouth to Edna. Siltation and

chemical pollution were noted as problems, and one 1-m high diversion dam functioned as a

barrier to fish movements.

Yet, juvenile steelhead were observed in the upper half of Pismo Creek during a CDFG

electrofishing survey on 26 June 1974. This distribution was essentially confirmed in another

survey conducted during the summer and fall of 1974 (Rohde 1975); juvenile steelhead were

found in lowermost West Corral de Piedra Creek and in the lower mid-portion of Pismo Creek,

but not in the lowermost main stem or estuary.

Based on a cursory review of CDFG file documents regarding a variety of development

projects in and around Pismo Creek, it is likely that steelhead habitat has continued to degrade in

especially the lower portion of the creek. Steelhead apparently still enter Pismo Creek, as based

on their mention in recent (1990) CDFG file documents.

East and West Corral de Piedra creeks. Both East and West Corral de Piedra creeks have

historically supported rainbow trout and at least small runs of steelhead (e.g. Jordan 1895). As

of 1985, a dysfunctional fish ladder on East Corral de Piedra Creek, built by the railroad in about

1927, blocked adult steelhead immigration to the upper stream (P. Chappell, CDFG, unpubl.

memo. of 24 June 1985). This barrier was judged to have a “serious deleterious effect on the

population.”

Steelhead reportedly spawned in the vicinity of a proposed dam site in West Corral de

Piedra Creek during the winter of 1961-62, and juveniles (5–10 cm in length) were common in

the 1.6 km section of live stream below the dam site the following September (R. N. Hinton,

CDFG, unpubl. memo. of 4 October 1962). In addition, rainbow trout were observed in 3.2 km

of live stream in the canyon above the dam site. The dam application was not protested by the

CDFG, and a fishway on the dam was deemed unnecessary, but a minimum release flow was

secured in the agreement. The last observation of juvenile steelhead was in lowermost West

Corral de Piedra Creek in 1974 (Rohde 1975). Resident rainbow trout, up to 20 cm long, have

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been observed in the tributaries above the reservoir as recently as December 1989 (K. Worcester,

CDFG, pers. obs.). Two upper tributaries provided excellent salmonid habitat for at least 1.3

km, even at the low flow stage observed. Much of the stream below the reservoir was dry or

otherwise degraded, and no fish were observed.

Salinas River Drainage (see Monterey County)

San Carpojo (San Carpoforo) Creek Most of the San Carpojo Creek drainage lies on property owned by the Hearst

Corporation, and as of 1948 was noted as having a self-sustaining steelhead population. Public

access to the stream is restricted. Surficial flow is normally interrupted in the lower stream in

summer. Juvenile steelhead, ranging in length from 5 to 20 cm, were seen in the lower stream in

June 1948, July 1952, and January 1960 when observations were made. In June 1960, the

visually-estimated density of 7.5–15 cm juvenile steelhead at two locations in the lower stream

was about 3.3 trout/m. The 7.5 cm fish were apparently greater in abundance than the 15 cm

fish.

The CDFG surveyed the lowermost 6.5 km of the San Carpojo during 24–25 January

1961. Stream flow was intermittent in the lowermost 1.6 km. Suitable spawning areas were

found throughout the stream, and were of excellent quality in the lower stream. High quality

rearing habitat, in the form of pools and cover, was available in the upper creek area. Two small

diversions were present, and several potential migration barriers near Windy Point were noted.

Juvenile steelhead were noted as scarce in the upper stream where excellent cover may have hid

them, but common in the lower 1.6 km of stream (estimated visually at 31–62 trout/km). One

adult was reportedly seen in the stream’s lagoon. A local resident reported that fingerling

steelhead were common throughout the stream in summer, but most emigrated during the first

rain of the season. In addition, he reportedly counted 155 adult steelhead in three holes in the

lower stream, and claimed that the largest adults entered the stream to spawn in January and

February, and smaller (30–51 cm), more silvery adults in March. Fishing intensity was heavy at

the mouth but light upstream because of restricted access. Overall, the San Carpojo appeared to

be a good steelhead spawning and nursery area.

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In July 1972, 23 adult (53–84 cm) and 350 juvenile steelhead were rescued from a drying

pool in the stream and released further upstream in an area with perennial flow (J. Schuler and

K. Boettcher, CDFG, unpubl. memo.)

The CDFG surveyed the San Carpojo during 23–24 July 1973. Stream flow was

interrupted at that time. Spawning gravels were present throughout the stream, and rearing

habitat, in the form of pools and cover, was abundant. No water diversions were observed.

There may have been minor pollution in the lower creek area from livestock feces, but siltation

was not a problem. Juvenile steelhead/rainbow trout, 5–25 cm in length, were captured by

electrofishing. The trout were very abundant, both above and below a 2+ m high waterfall in the

mid-section of the stream. Up to 20–25 trout occurred in 28 m2 pools. All trout observed were

infested with encysted metacercaria of the monogenetic trematode, Neascus, a condition

commonly referred to as “black spot disease”. A local resident reported that he had seen black

spot disease on the trout since about 1932. He also mentioned that the steelhead population had

been supplemented with juvenile plants during the late 1930’s or early 1940’s, which

corresponds with the time that rescued steelhead from the Santa Ynez River were being planted

in San Luis Obispo County streams. The waterfall was judged to be a barrier to immigrating

adult steelhead, at least under low flow conditions. It was assumed that resident rainbow trout

occurred above the waterfall and probably into the lower portion of the stream below the fall

where juvenile steelhead were also present. Again, fishing for adult steelhead was noted as

heavy in the lagoon; fishing for juvenile steelhead and resident rainbow trout in upstream areas

was probably light. The stream at this time was rated as one of the best steelhead streams in San

Luis Obispo County.

Some 27 adult steelhead were counted in three pools by a local resident in April 1974.

Follow-up observations were made of seven adult steelhead in the pools in question; the fish

ranged in length from 43 to 76 cm and several redds were observed in a nearby riffle (M.

Seefeldt, CDFG, unpubl. field report).

During 17 August–22 October 1978, Knable (1978) estimated juvenile steelhead

abundance and biomass in San Carpojo Creek and five other San Luis Obispo County coastal

streams. The San Carpojo was selected to represent a steelhead production system approximating

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pristine conditions. Abundance and biomass were estimated using electrofishing and the two-

pass removal method in six randomly-selected, 30.5 m long sections, in two 1.6 km long stream

reaches, between the mouth and the waterfall barrier at SKM 8.2. Portions of the lower creek

were dry.

Mean estimated juvenile density was 187 ± 344 trout/100 m (range, 0–1,063 trout/100

m), although this was an overestimate due to poor depletions with the two-pass removal method.

Juvenile recruitment in 1978 was relatively good as 50% of sampled trout (n = 150) were likely

young-of-the-year (50 –99 mm in length), 45% were 100–149 mm, and 4% were 150–249 mm.

Most sampled trout were young-of-the-year as average individual mass was 3.5 g.

Knable (1978) concluded that San Carpojo Creek remained basically unaltered, relative

to the other creeks in his survey. The most significant impacts were from extensive vegetation

clearing, channelization, and gravel mining within the lowermost 1.6 km of the creek.

San Carpojo Creek is reportedly still in prime condition (J. Nelson, CDFG, pers. comm.

regarding results of 1993 stream survey) and, along with the Arroyo de la Cruz, continues to be

among the most important steelhead streams in San Luis Obispo County.

Estrada Creek

The lowermost 0.4 km of the San Carpojo tributary, Estrada Creek, was surveyed by the

CDFG on 25 January 1961. Spawning substrate occurred only in scattered patches, but rearing

habitat, in the form of pools and cover, was adequate and juvenile steelhead (5–10 cm) were

present at a low density. No migration barriers, diversions, or pollution were observed in this

reach.

San Luis Obispo Creek Drainage Historically, the San Luis Obispo Creek system has supported steelhead, and rainbow

trout in the mountainous headwaters (Jordan 1895). The upper mid-portion of the creek flows

through the city of San Luis Obispo. Agricultural lands border the creek, both upstream and

downstream from the city. The CDFG surveyed the lowermost 11 km of the creek during 2–3

September 1958. Spawning gravel was mostly lacking in this lower area, but rearing habitat in

the form of pools and cover was abundant. There were no barriers to migration. Agricultural

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diversions occasionally caused interrupted flow conditions. Urban runoff, effluent from the San

Luis Obispo Sewage Treatment Plant, and an oil pipeline leak were pollution sources. No

steelhead were seen, although this area was regarded as steelhead rearing habitat. Angling

pressure for steelhead was reportedly heavy in the winter.

When surveyed again by the CDFG during 12–16 December 1960, conditions in the

lowermost 11 km of the creek were apparently much the same. Spawning habitat was generally

more abundant in the remaining 13 km of stream to the headwaters. Rearing habitat, in the form

of pools and cover, was generally available throughout, but still of highest quality in the lower

stream. There was a 1.5 m waterfall just upstream from the confluence with Reservoir Canyon

Creek which may have posed a barrier to upstream migration under low-flow conditions. There

were no diversions or pollution in the headwaters, whereas pollution from urban debris and

runoff, and effluent from the sewage treatment plant may have limited steelhead use of the

middle and lower stream areas. Several pumps and storage tanks were present along the lower

creek where water was diverted for agricultural irrigation. Juvenile steelhead/rainbow trout, 2.5–

20 cm long, occurred in the headwater section at a low population density. No trout were

captured in net samples farther downstream. Angling pressure for steelhead was still reportedly

heavy during the winter and early spring.

During May–August 1966, the CDFG investigated the effect of waste discharges on the

biologial resources of San Luis Obispo Creek, with emphasis on steelhead (Nokes 1966). Along

a 3.2 km reach within the city of San Luis Obispo, about 90 pipes, culverts, and drains were

observed which opened to the creek. A variety of chemical and organic pollutants were

discharging directly into the stream, including chlorinated swimming pool effluent and food-

laden kitchen drain effluents. Urban debris also heavily littered the stream.

Discharge from the San Luis Obispo Sewage Treatment Plant appeared to have the

greatest single effect on the distribution and site-specific abundance of aquatic organisms.

Effluent from the treatment plant sustained a continuous stream flow in the lower creek during

the summer–fall low flow period, when stream flow upstream from that point became

interrupted. Nokes (1966) found that the creek was relatively void of clean-water indicator

species of algae, invertebrates, and fishes along a 2.4 km reach downstream from the point of

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discharge. Densities of juvenile steelhead on 5 May 1966, as determined by cresol sampling in

blocked-off stream sections, were low (13–26 trout/100 m) at three stations in the middle to

lower creek. These fish ranged in length from 6.5 to 30.5 cm. In an instream bioassay

conducted during 24–28 August 1966, all rainbow trout held in the treatment plant discharge

which contained a high concentration of residual chlorine, and in the creek just downstream from

the point of discharge, died within 0.5 hr. Those held in the creek just upstream from the point

of discharge survived the 96 hr trial.

Overall, about 6.4 km of San Luis Obispo Creek, through the city of San Luis Obispo and

downstream from the sewage treatment plant discharge, were adversely affected by waste

discharges. Nokes (1966) predicted that the pollution effect would be even more widespread as

stream flow continued to decrease and waste discharges made up an even greater proportion of

the flow.

During the 1972-73 steelhead season, the CDFG in collaboration with students at the

California Polytechnic State University conducted a study to (i) estimate the adult steelhead run

size in San Luis Obispo Creek, and (ii) determine the approximate distribution of steelhead

spawning in the drainage (Schuler 1973). A trap to capture adult steelhead on their upstream

migration was operated at Marre’s dam, located about 1.6 km from the creek mouth, from 27

November 1972 through 10 February 1973. Adults were captured from 21 December 1972

through 6 February 1973, although 85% of adults were captured during 9–13 January 1973; high

flow displaced the trap during 17–26 January 1973. A total of 45 steelhead was captured, of

which 40 were tagged and released to estimate the adult run using the Lincoln-Petersen mark-

and-recapture method. Only trout ≥ 46 cm FL were considered steelhead, although this was later

considered a mistake. Apparently, the trap was ineffective in capturing steelhead spawners

between 35 cm and 46 cm, and so these smaller, younger adults were underestimated in the

catch. Captured males averaged (± SD) 66.9 ± 4.4 cm FL (range, 55.9–73.7 cm FL, n = 14),

females averaged 66.5 ± 5.0 cm FL (range, 55.9–76.2 cm FL, n = 13), and steelhead of

undetermined sex averaged 63.2 ± 7.2 cm FL (range, 45.7–73.7 cm FL, n = 13). There was no

significant difference in fork lengths among these three groups (ANOVA, F = 1.687, p = 0.199).

Two estimates of adult run size, 102 and 117 (95% C.L., 22–212), were derived using

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electrofishing and creel census as recapture methods, respectively. Both numbers were

considered underestimates, and Schuler guessed the run was closer to 200 fish during a good

year. The San Luis Obispo Creek tributaries, See Canyon, Stenner, and Brizziolari creeks, were

judged to be the areas used most by steelhead spawners, based on observations of young-of-the-

year steelhead made during electrofishing surveys.

The study was repeated during the 1973-74 season (Schuler 1974). Trapping was

conducted at Marre’s dam for 86 days, ending 2 March 1974. Only 13 adult steelhead were

captured, tagged, and released. In recapture efforts, 18 adults were captured by electrofishing of

which two were recaptures, and 17 adults were seen in a creel census of which three were

recaptures. The Petersen run size estimate corresponding to each recapture method was 117

(95% C.L., 9–223) and 58 (12–104), respectively, the latter being a partial estimate since the

fishing season ended before the adult upstream migration was completed. The 18 adults

captured by electrofishing were distributed as follows: six in San Luis Obispo Creek, 10 in See

Canyon Creek, and two in Stenner Creek (c.f. young-of-the-year steelhead observations in 1972-

73 study, above). Males observed in this study tended to be smaller on average (49.5 ± 10.7 cm

FL; range, 38.1–71.1 cm FL; n = 19) than females (55.5 ± 11.0 cm FL; range, 36.8–68.6 cm FL;

n = 19) but this difference was not statistically significant (Mann-Whitney U test, p = 0.09).

Based on ageing from scales, the total ages of spawners were 3–5 yr, with an overall average of

3.84 yr (calculated as in Fahy 1978). Males on average (3.63 yr) tended to be younger than

females (4.05 yr), but this difference was not statistically significant (Χ² = 4.255, DF = 2, p =

0.12). Scale reading also showed that most juveniles emigrated to sea at age 1(+), and that five

of 19 (26%) females and one of 19 (5%) males were repeat spawners. Age 3 spawners averaged

(± SD) 40.8 ± 2.8 cm FL (range, 36.8–45.7 cm FL; n = 11), age 4 spawners averaged 54.8 ±

8.7 cm FL (range, 39.4–68.6 cm FL; n = 22) and age 5 spawners averaged 68.3 ± 1.9 cm FL

(range, 66.0–71.1 cm FL; n = 5). The sport fishery was poor; there was an estimated 19

steelhead caught by 540 anglers who fished about 1,555 hr (0.012 fish/angler hr, 0.035

fish/angler). The decline in the San Luis Obispo Creek steelhead population was primarily

attributed to (i) a lack of juvenile steelhead rearing habitat in the form of pools and overhead

cover (e.g. riparian vegetation, undercut banks); (ii) poor water quality in the lower creek

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downstream from the discharge point of the San Luis Obispo Sewage Treatment Plant (see

summary of Nokes 1966, above); and (iii) man-made migration barriers that blocked access to

spawning and rearing habitats in tributaries.

Barclay (1975) reported juvenile steelhead/rainbow trout in San Luis Obispo Creek, and

“they were abundant in areas with clean, cool waters that flowed over gravel or other rock

substrate.” Rutten (1975) gave a more detailed presentation of the data collected under Barclay’s

direction. Sampling occurred between 17 June 1975 and 1 July 1975. Juvenile

steelhead/rainbow trout occurred in the lowermost main stem near Marre’s dam and just

upstream from the confluence with See Canyon Creek, and at nine mainstem stations from about

180 m above the sewage treatment plant outfall to the headwaters. Observed densities in the

main stem up to the confluence with Stenner Creek averaged (± SD) 13 ± 16 trout/100 m, while

those in upper San Luis Obispo Creek and the tributaries, See Canyon, Stenner, Brizziolari, and

Reservoir Canyon creeks, averaged 174 ± 148 trout/100 m. This difference in juvenile

steelhead/rainbow trout densities was highly significant (Mann-Whitney U test, p<0.001), and

reflected the disparity in trout habitat quality between the impacted main stem and relatively

undeveloped tributaries and headwaters. For example, the adverse effect of the treatment plant

effluent on juvenile steelhead distribution in the lower creek persisted.

The CDFG evaluated the steelhead resources of San Luis Obispo Creek in relation to a

proposed flood control project (Snider and Gerdes 1975). It was noted that mainstem steelhead

habitat was already degraded by existing flood control improvements such as bank revetment,

channelization, and tunneling. The juvenile steelhead population was studied during the late

summer–fall low flow period in 1975, when rearing habitat quantity and quality were

presumably most limited. Steelhead had access to suitable spawning habitat in the upper main

stem (above the confluence with Stenner Creek), and in the tributaries, See Canyon, Stenner,

Brizziolari, and Reservoir Canyon creeks. Qualitative surveys revealed the presence of juvenile

steelhead in nearly all stream areas with surficial flow. Abundance estimates were made, by use

of electrofishing and the two-pass depletion method, in six 30.5 m stream sections per 1.6 km

reach of each major steelhead rearing area identified in the qualitative survey. The highest

densities of juvenile steelhead corresponded to the main spawning areas. The average density in

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upper San Luis Obispo Creek was 269 trout/100 m, while those in See Canyon, Stenner, and

Reservoir Canyon creeks ranged from 249 to 981 trout/100 m (see below for details on each

tributary). The average length and biomass of juvenile steelhead were 87 mm FL and 1.8 kg/100

m, respectively, in the upper main stem, and had ranges of 56 –95 mm FL and 0.6–4.2 kg/100 m,

respectively, in the tributaries. In upper San Luis Obispo Creek, 77% of sampled trout were age

0+, 22% were age 1+, and 1% was age 2+. Corresponding percentages in the tributaries averaged

91.3%, 8.3%, and 0.3%, respectively. Based on age-class specific survival rates from

Shapovalov and Taft (1954), observed juvenile production in upper San Luis Obispo Creek

would correspond to an adult steelhead production on the order of 179 fish, while those in the

tributaries averaged 275 fish, resulting in an estimated drainage production of about 1,000 adult

steelhead. Snider and Gerdes (1975) noted that the most significant factor affecting steelhead

production in the San Luis Obispo Creek drainage was the availability of suitable juvenile

rearing habitat.

Eckle (1978) reaffirmed the negative impact of the San Luis Obispo Sewage Treatment

Plant on juvenile steelhead rearing habitat quality in lower San Luis Obispo Creek. Chloramine

toxicity rendered between 1.6 and 6.4 km of stream below the point of waste discharge

unsuitable as steelhead rearing habitat, as determined by instream bioassays conducted under

low flow conditions in August 1978. It was also suggested that chloramines could be a deterrent

to upstream migrating adult steelhead in low flow years, when a water quality barrier might

persist in the absence of sufficient dilution from rain runoff.

As of 1985, the best spawning and rearing habitats in the drainage were still in the

tributaries, See Canyon, Stenner, and Reservoir Canyon creeks, and upper San Luis Obispo

Creek above the urban area. Juvenile steelhead densities in the main stem above the San Luis

Obispo Sewage Treatment Plant ranged from 186 to 311 trout/100 m, while those in the

tributaries ranged from 435 to 808 trout/100 m (P. Chappell, CDFG, unpubl. data from a 1985

electrofishing survey, as cited in Western Ecological Services Company, Inc. 1987). No juvenile

steelhead were found at three locations on San Luis Obispo Creek below the treatment plant, as

far downstream as the Highway 101 bridge near Avila Road.

Cannata (1989) conducted a survey of San Luis Obispo Creek to determine if steelhead

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still used the stream as spawning and rearing habitat within the San Luis Obispo city limits.

Young-of-the-year (<75 mm TL) and older (≥ age 1+; >75 mm TL) steelhead were counted

while walking along the streambank during April–May 1989, thus providing a conservative

juvenile population count. About 800 young-of-the-year and 20 older steelhead were counted.

Thus, spawning was successful in at least two consecutive years. Steelhead occurred in all

sections of the survey area except below the point of discharge of the San Luis Obispo Sewage

Treatment Plant. When surveyed again during September–October 1989, stream flow was

interrupted and only a short section of stream within the San Luis Obispo city limits continued to

provide habitat for juvenile steelhead. Cannata (1989) concluded that, as of 1989, San Luis

Obispo Creek continued to support a steelhead population, but that the population was likely

depressed due to the effects of three consecutive years of drought (1986-87 through 1988-89).

Steelhead used the portion of the creek within the San Luis Obispo city limits as a migration

corridor, and as spawning and rearing habitats.

Young-of-the-year steelhead were observed in pools in lower San Luis Obispo Creek,

downstream from the city’s sewage treatment plant, during an electrofishing survey on 4 May

1994 (J. Nelson, CDFG, pers. comm. of 12 May 1994).

Castro Canyon Creek

Castro Canyon Creek is a very small, 2.4 km long tributary that enters lower San Luis

Obispo Creek about 6.4 km upstream from the Pacific Ocean. The creek was surveyed in its

entirety by the CDFG on 14 December 1960. Stream flow was very low at the time of the

survey, but suitable spawning and rearing habitats would be available to steelhead under higher

flow conditions. No barriers, diversions, or pollution were observed. The local CDFG warden

reportedly rescued large steelhead from the creek in some years. Local residents reported that

adult steelhead ascended the creek in wet years, but that none had been seen in several years.

Nor were any juvenile steelhead seen during this survey.

Harford Canyon Creek

Harford Canyon Creek is a very small, 3.2 km long tributary that enters the tidal zone of

lower San Luis Obispo Creek about 180 m upstream from the mouth. The creek was surveyed in

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its entirety by the CDFG on 13 December 1960. Spawning habitat was only fair as the substrate

contained much sand and silt. Rearing habitat in the form of pools and cover was adequate. No

barriers, diversions, or pollution were observed. Juvenile steelhead, 2.5–10.0 cm in length, were

seen, and local residents reported that the creek had “always” supported numerous small trout.

Prefumo Creek

Prefumo Creek is a main tributary that enters the mid-portion of San Luis Obispo Creek.

The entire 8 km of the creek was surveyed by the CDFG on 14 December 1960. Stream flow

was interrupted at the time of the survey. High quality spawning grounds were available in the

lower creek, and steelhead rearing habitat, in the form of pools and cover, occurred throughout

the stream. No diversions, barriers, or pollution were observed. Although no fish were captured

in net samples, the local CDFG warden indicated that adult steelhead did run in the creek in wet

years.

Schuler (1973) captured no adult steelhead by electrofishing in Prefumo Creek above

Laguna Lake during the 1973-74 season. Evidently, a concrete spillway and culvert under Los

Osos Road blocked the upstream migration of adult steelhead above Laguna Lake. Rutten

(1975) also found no juvenile steelhead in Prefumo Creek during the latter half of June 1975, at

an electrofishing station in the lowermost creek.

In contrast, young-of-the-year steelhead were inhabiting all available habitat in Prefumo

Creek when observed by the CDFG in October 1980 (P. P. Chappell, CDFG, unpubl. memo. of

14 October 1980). Every pool contained trout with densities ranging from 10 to 50 fish/pool,

depending on pool size.

Cannata (1989) saw no juvenile steelhead in lower Prefumo Creek while walking along

the streambank during April–May 1989. Apparently, the overpass structure at Highway 101

created a barrier that prevented adult steelhead from migrating to upstream spawning habitat.

Steelhead and rainbow trout were mentioned as fishery resources to be protected in a

recent (1990) CDFG file document, in connection with a proposed development project in the

creek drainage.

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Reservoir Canyon Creek

Reservoir Canyon Creek is an extreme headwater tributary to San Luis Obispo Creek.

Steelhead were present in the creek during a mid-1930’s CDFG survey. Spawning grounds were

described as patchy. The stream was regarded as the best steelhead production area in the San

Luis Obispo Creek system. Although no records were discovered, plants of juvenile steelhead

had apparently been made, the origin of these fish unknown. Brown trout had been introduced to

the creek (4,000 planted in 1933), but with poor results. Angling pressure on the creek was rated

as very heavy.

The report of a CDFG survey conducted on 16 December 1960 provided an impression of

how a dam in the system affected historical steelhead production. The earth-fill dam creating a

small reservoir restricted potential steelhead production to only about 0.8 km of the lower stream

area. Most of the water in the stream was diverted by the City of San Luis Obispo for domestic

use. At the time of the survey, stream flow was intermittent, rearing pools were small and

scattered, but cover from overhanging vegetation was abundant. A very sparse population of

small rainbow trout, 2.5–10 cm long, occurred in the upper canyon above the reservoir. The

reservoir was stocked with 12,000 catchable rainbow trout annually.

Rutten (1975) determined juvenile steelhead/rainbow trout abundance at three

electrofishing stations on the creek, two below and one above the big falls in Reservoir Canyon,

between 17 June 1975 and 1 July 1975. The density of juvenile steelhead below the falls

averaged (± SD) 294 ± 21 trout/100 m, while the density of rainbow trout at the one station

above the falls was 26 trout/100 m.

The CDFG also made juvenile steelhead abundance estimates in Reservoir Canyon Creek

downstream from the falls in 1975, by use of electrofishing and the two-pass depletion method

(Snider and Gerdes 1975). During June 1975 when stream flow in the creek was continuous, the

average density was 348 trout/100 m. By fall 1975, however, only 0.4 km of surface water

persisted in the creek and the average density of juvenile steelhead nearly tripled to 981

trout/100 m, apparently due to crowding as a result of the reduction in rearing habitat

availability. The average length and biomass of these fish in fall were 70 mm FL and 4.2 kg/100

m, respectively, and 94% of sampled trout were young-of-the-year and the remaining 6% were

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yearlings. Based on age-class specific survival rates from Shapovalov and Taft (1954), the

observed juvenile production in Reservoir Canyon Creek corresponded to an adult steelhead

production on the order of 91 fish.

As of 1985, some of the best spawning and rearing habitats in the drainage still occurred

in Reservoir Canyon Creek. At that time, the creek supported >435 trout/100 m (P. Chappell,

CDFG, unpubl. data from a 1985 electrofishing survey, as cited in Western Ecological Services

Company, Inc. 1987), which was a similar production level as in 1975.

See Canyon Creek

See Canyon Creek is an important, 7 km long tributary that enters the tidal zone of San

Luis Obispo Creek about 3.4 km upstream from the Pacific Ocean. Steelhead were present in the

creek during a mid-1930’s CDFG survey. Spawning grounds were “common” and overhanging

riparian vegetation and an abundance of insects apparently provided good rearing conditions for

juvenile steelhead. No barriers or diversions were seen. Angling pressure was noted as heavy.

The steelhead population had been supplemented with a plant of 8,000 juveniles in 1932.

When surveyed in its entirety by the CDFG on 12 December 1960, there was still high

quality spawning gravel throughout the creek. Suitable rearing habitat, in the form of pools and

overhanging vegetation, was also widespread. There were several agricultural diversions, and

urban debris polluted the stream. “A fair size population” of juvenile steelhead was observed.

These fish were visually estimated to be 2.5–20.0 cm in length. Local residents reported that as

many as several hundred adult steelhead ascended See Canyon Creek in wet years, but only a

few in dry years. The creek was regarded as the most important spawning tributary in the San

Luis Obispo Creek drainage.

Schuler (1973) captured six adult steelhead in See Canyon Creek by electrofishing during

22–25 February 1973. Observations of young-of-the-year steelhead made during this survey

also supported the view that the creek was an important spawning and rearing tributary for San

Luis Obispo Creek steelhead. During the 1973-74 season, 10 adult steelhead were captured by

electrofishing (Schuler 1974), thus demonstrating the continued persistent use of this stream as a

steelhead production area.

Rutten (1975) sampled six stations throughout See Canyon Creek by electrofishing,

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between 17 June 1975 and 1 July 1975. Densities of juvenile steelhead were relatively high and

averaged (± SD) 277 ± 163 trout/100 m (range, 161–584 trout/100 m). Juvenile population

density remained essentially the same into fall 1975 when the CDFG found an average of 302

trout/100 m, by use of electrofishing and the two-pass depletion method (Snider and Gerdes

1975). The average length and biomass of these fish were 56 mm FL and 0.6 kg/100 m,

respectively, and 97% of sampled trout were young-of-the-year and the remaining 3% were

yearlings. Based on age-class specific survival rates from Shapovalov and Taft (1954), the

observed juvenile production in See Canyon Creek corresponded to an adult steelhead

production on the order of 486 fish, making this stream the area of greatest steelhead production

in the San Luis Obispo Creek drainage.

As of 1985, some of the best spawning and rearing habitats in the drainage still occurred

in See Canyon Creek. At that time, the creek supported 435 –808 trout/100 m (P. Chappell,

CDFG, unpubl. data from a 1985 electrofishing survey, as cited in Western Ecological Services

Company, Inc. 1987), which at least equalled the production seen in 1975.

Stenner Creek

Stenner Creek is a major, 9.7 km long headwater tributary that enters San Luis Obispo

Creek within the city limits of San Luis Obispo. The creek was surveyed in its entirety by the

CDFG on 16 December 1960. Suitable spawning substrate occurred throughout the creek, and

was of highest quality in the middle portion just outside the city limits. Rearing habitat quality

was limited by a scarcity of pools throughout, and lack of riparian cover in the middle portion of

the creek. No barriers, diversions, or pollution were observed. Although no fish were observed,

the creek was regarded as potentially “a fair producer of steelhead especially during wet years.”

Schuler (1973) captured one adult steelhead in Stenner Creek during an electrofishing

survey on 9 March 1973. Young-of-the-year steelhead were also observed in both Stenner and

its tributary, Brizziolari Creek, during this survey. Schuler suggested that the Stenner Creek

system was one of the areas used most by San Luis Obispo Creek steelhead.

During 16–18 May 1973, the CDFG surveyed a reach of Stenner Creek from 1.6 km

below to 1.6 km above its confluence with the tributary, Brizziolari Creek. The upper 1.6 km

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section flowed through agricultural land, while the lower 1.6 km section flowed through an

urbanized area. An estimated third of the streambed within the survey sections consisted of

suitable spawning gravel. Rearing habitat in the form of pools, undercut banks, and overhanging

riparian vegetation was abundant. Perennial flow maintained pools and other low-velocity

rearing habitat even in dry years. Several migration barriers were observed, including summer

dams, but none appeared to affect adult steelhead movements. No diversions were seen. Storm

drains entering the creek were a potential pollution source. Agricultural waste water appeared to

enhance eutrophication of the stream, and resultant algal growth limited steelhead rearing habitat

utility. Silt entered the stream from Brizziolari Creek and extended downstream as far as 275–

365 m. Young-of-the-year and yearling steelhead were sampled by electrofishing. Estimated

abundance of both age classes combined, using the two-pass removal method, was low, about 10

trout/100 m. There was an estimated 6.4 km of stream habitat suitable for steelhead production.

The stream supported a minor trout fishery, with most pressure from youngsters.

During the 1973-74 season, two adult steelhead were captured by electrofishing (Schuler

1974), thus demonstrating the continued persistent use of this stream as a steelhead production

area.

Rutten (1975) found only 16 trout/100 m at one electrofishing station in lower Stenner

Creek during the latter half of June 1975, but 131 trout/100 m in the upper creek. In fall 1975,

juvenile population density averaged 249 trout/100 m in several 30.5 m stream sections, as

determined by electrofishing and the two-pass depletion method (Snider and Gerdes 1975). The

average length and biomass of these fish were 95 mm FL and 2.5 kg/100 m, respectively, and

83% of sampled trout were age 0+, 16% were age 1+, and 1% was age 2+. Based on age-class

specific survival rates from Shapovalov and Taft (1954), the observed juvenile production in

Stenner Creek corresponded to an adult steelhead production on the order of 249 fish.

As of 1985, some of the best spawning and rearing habitats in the drainage still occurred

in Stenner Creek. At that time, the creek supported up to 435 trout/100 m (P. Chappell, CDFG,

unpubl. data from a 1985 electrofishing survey, as cited in Western Ecological Services

Company, Inc. 1987), which at least equalled the production seen in 1975.

Cannata (1989) counted eight young-of-the-year and one yearling steelhead while

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walking along the streambank on the lowermost 180 m of Stenner Creek, during April–May

1989.

The Stenner Creek tributary, Brizziolari Creek, was surveyed by the CDFG on 15 May

1973, from its confluence with Stenner Creek upstream through the California Polytechnic State

University campus. This portion of the drainage was highly developed and the creek passed

through agricultural land, and through several culverts beneath and along roadways, including

the construction site for a new road. There were some suitable spawning grounds in the upper

survey area, but silt covered suitable gravel downstream from the road construction site. Man-

made pools occurred downstream from the culverts and these, along with undercut banks and

overhanging riparian vegetation, provided rearing habitat for juvenile steelhead, even under

interrupted flow conditions. Such pools, though, were silted in below the construction site. No

diversions were seen. Silt polluted the stream from the construction site, and this siltation

apparently extended well into Stenner Creek (see above). Cattle fecal material was also a

pollution source which likely enhanced primary production in the stream. Resultant algal growth

limited steelhead rearing habitat utility through physical occlusion. Young-of-the-year and

yearling steelhead were sampled by electrofishing. Estimated abundance of both age classes

combined, using the two-pass removal method, was very low, about 5 trout/100 m. Rutten

(1975) found no trout at an electrofishing station in lower Brizziolari Creek during the latter half

of June 1975, but about 10 trout/100 m at a station in the upper creek.

As of 1985, a dysfunctional fish ladder on Brizziolari Creek on the California

Polytechnic State University campus blocked upstream migration of adult steelhead (P.

Chappell, CDFG, unpubl. memo. of 6 June 1985). There was an estimated reduction of about

7,000–10,000 juvenile steelhead annually over a 3–5 yr period. The barrier problem was

apparently rectified by the University as of 18 December 1985 (R. A. Tartaglia, California

Polytechnic State University, San Luis Obispo, unpubl. letter of 23 December 1985).

STATUS: Mention Froom Creek, the Buckley Road tributary, and other minor tributaries that

may have supported steelhead production but no longer do so because of barriers, etc. (see

Schuler 1974).

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San Simeon Creek Drainage San Simeon Creek has historically supported a steelhead population. Early records show

that steelhead were present in the creek when the CDFG surveyed the stream during the mid-

1930’s. Spawning grounds for steelhead were common except in the upper areas. The middle

and lower portions of the stream had apparently dried up in late summer over several years,

resulting in a loss of rearing habitat. No barriers or diversions were seen. Natural propagation

among migrant adults was noted to occur, but survival of progeny was predicted to be low,

presumably because of stream desiccation and heavy fishing pressure on steelhead juveniles.

Although the steelhead population had been supplemented with 10,000 juveniles in 1932 and

8,000 in 1933, the surveyors recommended against further stocking because of interrupted flow

conditions in late summer.

When San Simeon Creek was surveyed by the CDFG in June 1948, spawning substrate

was plentiful, and juvenile steelhead, 2.5–5 cm in length, were abundant and occurred at visually

estimated densities of 160–250 trout/100 m. A few planted rainbow trout were also observed. Based on inform

1950), the creek was planted with hatchery reared trout during 1947–1950 to support a stream

trout fishery. Fingerling plants were most often indicated but it was unclear if the fish planted

were from steelhead or rainbow trout stock. Planting of catchable rainbow trout was also

mentioned. There was much attention paid to the success of these plants relative to stream flow,

and the 1949 and 1950 plants in the North Fork San Simeon Creek were considered unsuccessful

because of interrupted flow conditions in late summer–fall. However, this headwater area

contained perennial pools with ample shading capable of providing over-summering habitat for

juvenile steelhead.

When the CDFG surveyed the lower creek area in September 1948 (H. D. Hoefelmeier,

CDFG, unpubl. field correspondence of 10 September 1948), the creek was completely dry for at

least 2.4 km upstream from the Highway 1 bridge. Isolated pools occurred above that point

which supported surviving fish. The lagoon at the mouth of the creek, downstream from the

Highway 1 bridge, contained the only water in the lower creek area. The local fish and game

warden participating in the survey indicated the lagoon would persist until winters rains began.

Hoefelmeier also noted that all the creeks from Morro Bay to Piedras Blancas Point had similar

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streamflow conditions at that time.

The lowermost 11 km of San Simeon Creek were surveyed by the CDFG on 19 January

1960. The lowermost 7 km contained a very high proportion of spawning gravel, visually

estimated at 80%–90% of the streambed. In the uppermost 4 km of the survey area, <30% of the

streambed overall contained suitable spawning gravel. The distribution of high quality rearing

habitat for juvenile steelhead, in the form of pools and cover (rootwads, fallen trees, overhanging

riparian vegetation, boulders), was essentially the opposite of that for spawning habitat, in that

the best rearing areas were in the uppermost 5 km of the survey area. A bedrock fall, about 320

m downstream from the confluence of the north and south forks, was a potential barrier to

upstream migration. However, it was apparently passable to adults under high flow conditions

because the local fish and game warden had seen steelhead in the south fork above the fall.

There were no diversions, and no pollution was seen although there was extensive cattle grazing

in the watershed. No fish were observed in the stream during this survey, but the stream was

characterized as providing “some of the better steelhead fishing for the San Luis Obispo area.”

In 1965, the CDFG investigated the effect of siltation from the Stewart Warren Mine on

juvenile steelhead production in Steiner and San Simeon creeks (M. L. Johnson, CDFG, unpubl.

memo. of 4 October 1965 and attached unpubl. file report on subject). Steiner Creek is a major

tributary that enters San Simeon Creek about 7 km upstream from the mouth. The mine

contributed silt to Steiner Creek which then carried it to San Simeon Creek below the confluence

with Steiner. On 8 June 1965, juvenile steelhead abundance was determined by creosol

sampling in one 20 m long section each in San Simeon Creek above the Steiner Creek

confluence, in Steiner Creek, and in San Simeon Creek below the confluence. (Visual

streambank counts were also made but it was later decided that creosol sampling gave the most

accurate results). The density estimate for the San Simeon Creek section above the confluence

was 994 trout/100 m, while those in Steiner Creek and San Simeon below the confluence were

114 and 94 trout/100 m, respectively. Thus, the data suggested that steelhead production in the

silted areas was lower than that in the unsilted area by a factor of nearly 10. Johnson expanded

the data for the entire 8 km section of Steiner Creek, and the 7 km of San Simeon Creek below

the confluence, and estimated a loss in juvenile steelhead production (at that recruitment stage)

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of about 137,500 fish.

The CDFG conducted a follow-up survey on 27 September 1965. The most significant

change in conditions was that San Simeon Creek was dry from the lagoon to 1.6 km upstream

from the Steiner Creek confluence, as was the lowermost 2.4 km of Steiner Creek. Juvenile

steelhead density in San Simeon Creek above the confluence was 809 trout/100 m, as determined

by creosol sampling in one 23 m long section. Thus, there was about a 20% reduction in density

since the June 1965 sampling occasion. Assuming the same density reduction rate in Steiner

Creek, and taking into consideration the rearing habitat loss in all of San Simeon Creek below

the confluence and in lower Steiner Creek due to desiccation, the estimated loss in juvenile

steelhead production (at this recruitment stage) because of siltation was calculated to be about

41,000 fish.

In 1970, the CDFG estimated the abundance of juvenile steelhead by electrofishing

several randomly-selected 30.5 m reaches in three 1.6-km sections (L. K. Puckett, CDFG,

unpubl. memo. of 30 December 1971). Abundance was estimated using the two-pass removal

method. Juvenile steelhead abundance ranged from 113 trout/100 m in the uppermost km to 653

trout/100 m in SKM 8 (SKM 3–5 were dry), and averaged 376 ± 270 trout/100 m among the

three sections.

San Simeon Creek was next surveyed by the CDFG during 13–14 August 1973, from the

headwaters to the lagoon for a distance of 14.5 km. The distribution of spawning and rearing

habitats was essentially the same as that described in the January 1960 survey (see above). No

new barriers to adult immigration or diversions were observed on the main stem, although farm

ponds withheld the water of some tributaries. The gravel quarrying operation of Morro Rock

and Sand disturbed the streambed at three locations downstream from Steiner Creek. Not only

was about 3.2 km of steelhead spawning habitat disturbed or eliminated, but the quarrying also

caused siltation. In addition, the gravel operations blocked the spring-time migration of young-

of-the-year steelhead from the desiccating lower stream to perennial rearing habitat upstream.

An abandoned mercury mine on a small tributary polluted the stream with silt and possibly

mercury, cattle fecal material contaminated the upper stream areas, and a public dump on the

lower San Simeon Creek tributary, Van Gordon Creek, contributed silt and trash to the drainage.

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Despite the relatively degraded condition of the creek, juvenile steelhead/rainbow trout, 4.0–

15.0 cm in length, were captured by electrofishing and netting in all sections of the main stem,

including the lagoon and above the bedrock barrier near the headwater forks. There were many

young-of-the-year in pools in the lower and middle creek areas, and the upper creek contained

both young-of-the-year and age 1+ fish but in relatively lower densities. San Simeon Creek was

still viewed as a valuable steelhead production area, but that its potential was compromised by

especially the gravel extraction activity.

Degradation of lower San Simeon Creek persisted in connection with gravel removal. In

discussing the problem, Chappell (1976) wrote that the loss of gravel and cobble, compaction of

the streambed, loss of riparian vegetation, road construction, and resultant sedimentation from

both instream sources and erosion of streamside soils would preclude the continued use of lower

San Simeon Creek as steelhead spawning and rearing habitat. Chappell also made two points of

broader interest: first, that juvenile steelhead in central California coastal streams, such as San

Simeon Creek, typically remained in the stream for only one year before smolting and

emigrating to the sea; and second, that small tributaries becoming intermittent in summer often

support steelhead spawning in winter, with resultant juveniles escaping downstream in spring to

perennial rearing areas.

During the 1983-84 steelhead season, the Santa Lucia Flyfishing Club conducted a creel

census of four San Luis Obispo County coastal streams, including San Simeon Creek (Santa

Lucia Flyfishing Club, San Luis Obispo, newsletter of April 1984). Surveys occurred on 20 of

the 50 legal fishing days. Seven anglers were interviewed who landed no steelhead during 6.50

hr of angling effort, although there were rumors of steelhead being taken.

Approximately 200 steelhead, ranging in size from 9 to 60 cm, died in the San Simeon

Creek lagoon on 9 August 1988, because of low water levels and resultant high temperature and

low dissolved oxygen concentration. Generally, though, the lagoon is used as rearing habitat by

juvenile steelhead when water quality is suitable (D. W. Alley, D. W. Alley and Associates, pers.

comm. of 21 January 1993). A few juvenile steelhead were observed in the lagoon and

lowermost 200 m or so of the creek during monthly snorkeling surveys beginning in May 1992,

although abundances of juvenile steelhead/rainbow trout were generally higher in upstream areas

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(M. Jennings, USFWS, pers. comm. of 21 January 1993).

The CDFG surveyed San Simeon Creek during 15–16 September 1992, from the

confluence of the north and south forks to a point 8 km downstream. Only the uppermost 3.2 km

of the survey area had surface flow and of this about 0.8 km was above the bedrock fall

described in earlier surveys (see above). The remainder of the stream in the survey area

contained only isolated pools of water. Contrary to stream survey reports through 1973, the

lowermost 3.2 km of the survey area contained extensive (≥ 30 m long) deposits of sand along

with boulders and cobble. This lower section still contained more spawning areas, relative to the

upstream area with water, but there was clearly a significant reduction in abundance of suitable

spawning gravel from previous surveys. Physical conditions for the provision of rearing habitat

were still intact but stream flow limited rearing habitat quantity and quality. No new barriers

were seen, nor were there any surface diversions, but there were several streamside wells that

pumped water from the underflow. Cattle polluted the stream with fecal material. Low densities

of young-of-the-year, age 1+, and possibly age 2+ juvenile steelhead/rainbow trout were seen in

the uppermost 3.2 km section with surface flow.

This stream survey was followed by an assessment of the stream habitat and juvenile

steelhead population in San Simeon Creek in 1993 (Nelson 1995). This work was conducted in

the perennial reach of stream from the Steiner Creek confluence at 6.4 km above the mouth, to

the bedrock fall at 9.3 km above the mouth. Stream flow within the perennial reach decreased

from 0.156 m3/s on 5 May 1993 to 0.013 m3/s on 1 November 1993; the lowermost 6.4 km of

the creek went dry during the latter half of July 1993. The perennial reach was habitat typed in

June 1993, and as a percentage of the total length, 46% was flatwater habitat (pocket waters,

glides, runs, step runs), 43% was pools, 7% was riffles, and 4% was cascades. Spawning areas

were sparse, small in size, and the substrate was either embedded or consisted of sand. Rearing

habitat was relatively abundant but not of high quality. Cover was adequate, but pools were

shallow as a result of the combined effects of low stream flow and sedimentation. The reach

contained one surface diversion. Sediment sources may have been a landslide on the north fork,

a construction site below the bedrock fall, five road crossings, and four cattle crossings. The

sediment problem had been exacerbated by a lack of flushing flows for 5 yr.

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Nelson (1995) sampled the juvenile steelhead population by use of a downstream migrant

trap and electrofishing. The downstream migrant trap was located at the upstream end of the

lagoon, and was fished from 7 April 1993 to 19 May 1993. Only 10 steelhead smolts were

captured during seven weeks of trapping, nine of which were captured during the weeks of 19

April 1993 and 26 April 1993. More smolts may have emigrated prior to the trapping period.

Captured smolts averaged (± SD) 181 ± 11 mm TL (range, 170–204 mm TL). Electrofishing

was conducted in 10-30.5 m long sections in the perennial reach during September 1993. A total

of 205 juvenile steelhead was captured, and the composite abundance estimate determined by the

multiple-pass removal method for all 10 sections was 218 trout. The expanded estimate for the

2.4 km long perennial reach was 1,726 trout, or about 72 trout/100 m. Captured steelhead

averaged 130 mm TL (range, 69–314 mm TL), and the length frequency distribution of the catch

(Nelson 1995) suggested that at least three consecutive year classes were represented, with the

1993 age 0+ group dominating in relative abundance. Nelson (1995) concluded that the San

Simeon Creek steelhead population was primarily limited by lack of stream flow during spring–

fall, and secondarily by sedimentation.

The habitat and juvenile steelhead population in the perennial reach of San Simeon Creek

were assessed again in September 1994 by Alley & Associates (1994). The perennial reach in

1994 was only 1.5 km long. Habitat typing affirmed the dominance of flatwater habitats and

pools, and the negative influence of sediment, as seen by Nelson (1994) in 1993. Using the

multiple-pass removal method, and weighing habitat-type specific densities of each age class by

the cumulative length of each habitat type in each of three reaches, there was a summed estimate

of 2,003 juvenile steelhead in the 1.5 km perennial reach, or 134 trout/100 m. Thus, the

estimated total number of juvenile steelhead in the perennial reach was very similar in

September 1993 (~1,700) and September 1994 (~2,000), but density in 1994 was nearly twice

that in 1993 (~130 trout/100 m vs. ~70 trout/100 m, respectively). The length of the perennial

reach was also about 38% shorter in 1994 than in 1993. Based on observed densities of juvenile

steelhead in September 1994, the corresponding number of adult steelhead that would be

produced was estimated at 65 fish, using a model developed by Kelley et al. (1987).

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Steiner Creek

Observations by biologists over the last 30 yr demonstrate the persistent use of the San

Simeon Creek tributary, Steiner Creek, as a steelhead production area. On 8 June 1965, the

CDFG estimated juvenile steelhead abundance in one 20 m long reach at 114 trout/100 m, in the

investigation of a siltation problem in the drainage (M. L. Johnson, CDFG, unpubl. memo. of 4

October 1965 and attached unpubl. file report on subject; see above for complete synopsis).

Juvenile steelhead, 5.0–12.5 cm in length, were observed in the creek near the dam site of the

proposed Cambria Meadow Reservoir when surveyed by the CDFG on 21 December 1989. In

September 1994, Alley & Associates (1994) assessed the habitat and juvenile steelhead

population in one 435 m long reach in the perennial portion of Steiner Creek. Perennial water

began about 5.6 km upstream from the confluence with San Simeon Creek. About 92% of the

surveyed reach was composed of step-runs and bedrock pools. Using the multiple-pass removal

method, and weighing habitat-type specific densities of each age class by the cumulative length

of each habitat type in the reach, there was a summed estimate of 1,145 juvenile steelhead in the

reach, or 263 trout/100 m. Based on observed densities of juvenile steelhead in September 1994,

the corresponding number of adult steelhead that would be produced was estimated at 31 fish,

using a model developed by Kelley et al. (1987).

Santa Rosa Creek Drainage Santa Rosa Creek is among the most well-known steelhead streams in San Luis Obispo

County. The CDFG surveyed the creek under low-flow conditions during the mid-1930’s.

Stream flow was perennial in the upper creek but became interrupted in the middle and lower

portions. No migration barriers were observed, and spawning grounds were common along the

stream. The steelhead population had apparently been supplemented with earlier plants, but a

stocking summary covering the early 1930’s showed only a plant of 4,000 brown trout made in

1933. The surveyors recommended against further stocking under low-flow conditions. They

also predicted that the success of natural spawning was limited because of low stream flow.

Fishing pressure had been heavy on the stream.

The CDFG stream survey files contained several miscellaneous notes about steelhead and

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their habitat in Santa Rosa Creek from the 1950’s. The opening of the summer trout season on 1

May 1950 included the take of many limits of juvenile steelhead/rainbow trout, about 12.5–23.0

cm in length. Some 3,000 rainbow trout were planted in the stream in April 1951. A creel

census conducted during January 1955 revealed that an estimated 650 angler days were spent to

catch over 600 steelhead at Santa Rosa Creek. Angling was confined to the tidewater portion of

the stream, and most captured fish were presumably juveniles, based on the magnitude of the

catch. During a brief check of the creek on 18 January 1957, suitable spawning gravel was seen

at the Highway 1 crossing. Several adult steelhead had reportedly been taken in the lagoon

during the previous week. On 29 April 1959, the CDFG observed a high abundance of 2.5–5.0

cm long steelhead fry and 10.0–18.0 cm long yearlings in the upper stream. For example, there

were a visually-estimated 150–200 fry and 30 yearlings in one 17 m3 pool.

A more comprehensive view of Santa Rosa Creek as a steelhead production area was

provided when the CDFG surveyed the lowermost 18 km of the stream on 18 January 1960.

Spawning areas were abundant and in good condition throughout the lowermost 10.6 km of

stream, and scattered further upstream. Rearing habitat, in the form of pools and cover, was of

high quality in the uppermost 3–5 km of the survey area. In contrast, pool development was

poor and cover lacking in the lowermost 14.5 km. Surface water was diverted to adjoining

ranches, and cattle grazing caused much erosion in the upper stream area. No juvenile

steelhead/rainbow trout were seen in the creek during this survey.

In a letter of concern to the CDFG (W. C. Weiss, Cambria, CA, unpubl. letter of 23

January 1960), a local resident described how ranchers in the upstream creek area built small

dams in summer each year for irrigation diversions. Stream flow, in the otherwise perennial

creek, became interrupted as a result. This problem occurred reportedly about four times

between 5 July 1959 and mid-October 1959, each time for 1–2 weeks. Many juvenile steelhead

and stocked rainbow trout were apparently killed as their oversummering pools dried up.

Similarly, on 24 June 1960, the CDFG found that stream flow in Santa Rosa Creek,

downstream from 4.7 km above the Highway 1 crossing, became interrupted as the result of a

surface diversion in that reach (M. R. Schreiber, CDFG, unpubl. field notes of 24 June 1960).

Young-of-the year steelhead, 2.5–7.5 cm long, were observed at high visually-determined

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densities in pools at each of 10 stations from the perennial upstream area, 15.8 km above

Highway 1, to isolated, desiccating pools in the lowermost creek within the town of Cambria. In

1961, these seasonal, interrupted flow conditions persisted through late fall when the CDFG

observed the stream on 19 December 1961, and saw six 5.0–10.0 cm long juvenile steelhead in a

pool about 4.5 km upstream from Highway 1.

In 1970, the CDFG evaluated the impact of summer trout fishing on the juvenile

steelhead population inhabiting the Santa Rosa Creek lagoon (L. Puckett, CDFG, unpubl. memo.

of 2 November 1970). The study consisted of (i) a mark-and-recapture estimate of the lagoon-

dwelling juvenile steelhead population; and (ii) an estimate of the number of steelhead removed

from the population by angling during the summer trout season as determined by a creel census.

Beginning in mid-February 1970 and continuing periodically through April 1970, juvenile

steelhead were seined in the lagoon, marked with an adipose fin clip and released. Juvenile

steelhead entering the lagoon were intercepted at a downstream migrant trap 1.6 km above the

lagoon. These fish too were marked and released. Trapping continued through July 1970,

although <50 trout were trapped over the entire period. Thus, most downstream movement must

have occurred prior to early March. Overall, 1,800 juvenile steelhead were marked and released.

The lagoon population was estimated to be 6,800 juvenile steelhead by the opening of the

trout season on 2 May 1970. An estimated 2,290 juvenile steelhead, or 34% of the lagoon

population, were captured during 2 May–31 August 1970, as determined by the creel census.

These fish averaged 13.0 cm in length. On a monthly basis, 1,960, 268, 61, and 0 trout were

caught in May, June, July, and August, respectively. The seasonal decrease in harvest reflected a

decline in use rather than catch rate, as catch rates throughout the period that fishing occurred

remained above 1.3 trout/hr. No angling took place in August 1970, yet at least several hundred

juvenile steelhead remained in the lagoon, as determined by seining.

Thus, of the estimated 6,800 steelhead present at the start of the trout season, roughly

50% were accounted for in the fishery (~2,300 trout) and as fish surviving the summer in the

lagoon (perhaps as many as 1,000 trout). The other half of the original population either escaped

to the ocean before the sandbar formed in early May, was lost to predation, or died as a result of

decreasing water quality with water temperature peaking at 25.6° C on warm calm days.

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Puckett concluded that the data did not support the need for a closure on summer trout fishing in

lagoons south of San Francisco, as the observed level of fishing mortality was not thought to

have a significant influence on adult run size, which he noted was about 500 fish. However,

current regulations prohibit summer trout fishing from San Francisco through San Luis Obispo

counties on coastal streams or portions thereof accessible to steelhead, including lagoons.

Bailey (1973) estimated the population size and biomass of juvenile steelhead in Santa

Rosa Creek during June–August 1970. The study area included the lowermost 19.3 km of the

stream. During this study period, stream flow in the creek was interrupted which resulted in

three dry sections, the most significant of which extended from about 11 to 13 km upstream from

the mouth. This dry section was used as a boundary zone between the upper and lower creek for

which post hoc comparisons were made. The lower creek lacked riparian vegetation, and was

relatively warm and eutrophicated. In contrast, the upper creek had dense riparian vegetation, an

abundance of riffles, and was relatively cool and oligotrophic. Juvenile steelhead/rainbow trout

abundance was estimated, by use of electrofishing and the two-pass removal method, in typically

four, randomly selected 30.5 m long sections in each of 11 contiguous, 1.6 km stream reaches.

Juvenile steelhead densities in individual sections were highly variable (range, 0–1,020

trout/100 m; c.v. = 88%), and averaged 345 ± 302 trout/100 m. Densities in the upper creek

averaged 535 ± 286 trout/100 m, while those in the lower creek averaged 202 ± 229 trout/100

m, and this difference was highly significant (Mann-Whitney U test, p<0.001)4. Individual

section density estimates were averaged and expanded for each 1.6 km reach, and it followed

that reach densities in the upper creek (5,336 ± 1,874 trout/km) were significantly greater

(Mann-Whitney U test, p<0.02) than those in the lower creek (2,117 ± 1,071 trout/km).

Average individual masses of trout in upper creek reaches (179 ± 48 trout/kg) were significantly

4 Note that sampling occurred from June to August, the period during which the size of the age 0 cohort is

typically regulated the most proportionately (reviewed by Titus 1990). Thus, the overall picture provided by Bailey (1973)

may have been somewhat confounded in that abundance and biomass estimates made at different locations and times likely

corresponded to different recruitment stages.

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lower (Mann-Whitney U test, p<0.03) than those in lower creek reaches (83 ± 47 trout/kg).

Thus, juvenile steelhead were typically more abundant per unit area and smaller in the upper

creek relative to the lower creek. With an average individual mass in the upper and lower creek

of 5.6 g and 12.0 g, respectively, most fish in the upper creek were young-of-the-year while

yearlings were proportionately more abundant in the lower creek. Interestingly, average total

biomass in upper creek reaches (29 ± 15 kg/km) did not differ significantly (Mann-Whitney U

test, p>0.85) from that in lower creek reaches (28 ± 18 kg/km). The total population estimate

and biomass for the study area was 63,378 trout and 504 kg. Bailey (1973) concluded (i) that

Santa Rosa Creek, on a per km basis, was the most productive among several central coast

steelhead streams surveyed during 1970–71 under the direction of the CDFG (L. K. Puckett,

CDFG, unpubl. memo. of 30 December 1971); and (ii) that water development posed the greatest

threat to the Santa Rosa Creek steelhead run.

On 2 February 1974, the CDFG observed three adult steelhead in the creek, about 6–8 km

above the mouth. The visually-estimated lengths of these fish were 41 cm, 64 cm, and 76 cm.

On 23 February 1974, the CDFG captured two spawning pairs of adult steelhead in Santa Rosa

Creek by electrofishing: the first pair consisted of a 79.8 cm female and 72.9 cm male, and the

second pair of a 61.0 cm female and a 51.3 cm male. On 24 February 1974, a 50.8 cm female

was captured on hook and line in the lagoon.

During 17 August–22 October 1978, Knable (1978) estimated juvenile steelhead

abundance and biomass in Santa Rosa Creek and five other San Luis Obispo County coastal

streams. Santa Rosa Creek was selected to represent a steelhead production system subject to a

moderate level of human-induced degradation. Similarly to Bailey (1973), abundance and

biomass were estimated, by use of electrofishing and the two-pass removal method, in six

randomly-selected 30.5 m long sections in each of five 1.6 km long stream reaches. Two reaches

each corresponded to the lower and upper creek areas described by Bailey (1973; see above), and

the fifth reach was in the boundary zone from about 11 to 13 km above the mouth.

As seen by Bailey (1973), individual section densities varied greatly (range, 0–105

trout/100 m; c.v. = 151%), but the average of 22 ± 33 trout/100 m was an entire order of

magnitude lower than that estimated by Bailey (1973) and this difference was highly significant

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(Mann-Whitney U test, p<0.001). As in 1970, densities in the upper creek (41 ± 40 trout/100 m)

tended to be higher than those in the lower creek (6 ± 11 trout/100 m), and this difference was

nearly significant (Mann-Whitney U test, p = 0.0525). Also consistent with Bailey (1973),

average individual masses of juvenile steelhead in upper creek sections (111 ± 68 trout/kg) were

significantly lower (Mann-Whitney U test, p<0.007) than those in lower creek sections (25 ± 7

trout/kg). Again, juvenile steelhead were typically more abundant per unit area and smaller in

the upper creek relative to the lower creek. With an average individual mass in the upper and

lower creek of 9.0 g and 40.0 g, respectively, most fish in the upper creek were young-of-the-

year while most of those in the lower creek were yearlings. Overall, of 161 trout sampled, 52%

were 50–99 mm in length, 31% were 100–149 mm, 16% were 150–199 mm, and 1% was 200–

249 mm. Also consistent with Bailey (1973) was the finding that average total biomass in upper

creek sections (446 ± 539 g/100 m) did not differ significantly (Mann-Whitney U test, p>0.58)

from that in lower creek reaches (330 ± 429 g/100 m).

Knable (1978) found that lower Santa Rosa Creek was evolving toward a state of

advanced degradation. The stream channel in the lower creek was eroding and broadening as a

result of streamside vegetation loss, caused by intense livestock grazing, urbanization, and

agricultural development. The quality of rearing habitat for juvenile steelhead was limited

because of the lack of cover. Spawning gravel occurred in the lowermost 13 km of the creek but

its utility was considered questionable because of insufficient cover. Suitable spawning gravel

and cover existed in the upper creek area, which had not been severely modified. The lower

creek, especially near Cambria, was polluted with urban debris which also reduced rearing

habitat quality. Stream flow was interrupted in many areas above stream kilometer 9.6. In

addition, the 1976–1977 drought likely exacerbated these negative impacts on steelhead habitat

and therefore the population.

Rathbun et al. (1991) presented a brief summary of up-to-date observations on steelhead

in Santa Rosa Creek, and indicated that juveniles were abundant in the drainage through the

early 1980’s, based on CDFG unpublished reports and field logs. Sport fishing effort for

returning adult steelhead was reportedly still intense at the mouth of the creek through 1986.

Angler observations and reports indicated that the number of adult steelhead entering the creek

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declined significantly from 1987 through 1991. During a qualitative survey in 1988, rainbow

trout were noted as “fairly numerous” in the upper watershed, but absent in lower Santa Rosa

Creek. Only a few juvenile steelhead were seen in one pool during a survey from the mouth to

the Main Street bridge in Cambria in March 1990. During 1988–1991, the CDFG received only

a few reports of spawning adults. No steelhead were seen during a survey of the lowermost 3.2

km of the creek in mid-July 1991. As of 1991, steelhead still spawned and reared in the upper

drainage, but the lagoon no longer functioned as important rearing habitat, especially during the

summer, as no steelhead had been seen there for years. It was apparent to Rathbun et al. (1991)

that overall steelhead abundance was “drastically reduced from historic numbers.” These

authors attributed the decline primarily to reduced habitat quality and quantity from loss of

instream flow and perennial holding pools in the lower creek, and to loss of flow to the lagoon,

as a result of increased agricultural and urban use of the water. The 1987–1992 drought

undoubtedly exacerbated the problem.

The lowermost 21 km of Santa Rosa Creek were surveyed by the CDFG from 28 April

1992 through 1 May 1992. The lowermost 4 km of the creek, where it flows through Cambria,

was somewhat urbanized, including pollution from urban debris. The next 9.7 km upstream

flowed through land developed for cattle grazing and crop production; cattle wastes were a

source of organic pollution and cattle use of the stream channel also caused streambank erosion

and sediment pollution as did poor agricultural practices. Many homes were built adjacent to the

creek. Extensive stretches of high quality spawning grounds, some over 30 m long, existed

throughout the drainage. Rearing habitat, in the form of pools and cover, also occurred

throughout the drainage. Steelhead had access to the lowermost 18 km of Santa Rosa Creek as

cascade falls in the headwaters blocked upstream migration of adult spawners. There was a log

jam about 13 km upstream from the lagoon but there was no indication if it was a migration

barrier. An elevated culvert at the mouth of the Santa Rosa Creek tributary, Curti Creek,

blocked upstream migration into that stream. Many surface water diversions were seen

throughout the drainage, in addition to wells on the stream banks which pumped from the

underflow. Juvenile steelhead/rainbow trout were present throughout the drainage, with the

exception of the uppermost 2.4 km of the study area. Young-of-the-year were abundant at only

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three locations in the upper creek. Yearling steelhead, ≥ 12.5 cm in length, were seen throughout

the system but not in great abundance. Santa Rosa Creek was still recognized as having been

one of the best steelhead production areas in San Luis Obispo. Lack of instream flow during the

summer and fall was considered the factor which most prevented the steelhead production

potential of the system from being met. Otherwise, restoration potential was high with regard to

problems associated with cattle grazing, crop production, and other development.

This stream survey was followed by a CDFG assessment of the juvenile steelhead

population and stream habitat in 1993 (Nelson 1994b). The study area included the lowermost

23 km of the creek. Stream flow at stream kilometer 16 in the upper creek area decreased from

0.214 m3/s on 5 May 1993 to 0.012 m3/s by 1 November 1993. At stream kilometer 3.2 in the

lower creek area, stream flow decreased from 0.301 m3/s on 5 May 1993 to 0.011 m3/s by 20

September 1993, at which time measurements were discontinued at that station due to

interrupted flow conditions.

Steelhead were sampled by use of a downstream migrant trap and electrofishing. The

downstream migrant trap was located at stream kilometer 1.9, and was fished from 26 April 1993

to 5 June 1993. Only one steelhead parr (76 mm TL), five smolts (158–247 mm TL), 13 rainbow

trout (174–300 mm TL), and three post-spawner adults (421–496 mm TL) were captured. More

smolts may have emigrated prior to the trapping period.

The electrofishing survey repeated the stratified random sampling method used by Bailey

(1973) and, to a lesser extent, Knable (1978). During 16 August–9 September 1993, abundance

and biomass were estimated, by use of the multiple-pass removal method, in six randomly-

selected 30.5 m long sections in each of 14 contiguous, 1.6 km long stream reaches. Seven

reaches corresponded to the lower creek area described by Bailey (1973), while six corresponded

to the upper creek area. As seen previously, individual section densities varied greatly (range,

0–433 trout/100 m; c.v. = 168%), and the average of 56 ± 94 trout/100 m represented the same

lower, order-of-magnitude difference in densities seen by Knable (1978), and this difference

relative to Bailey (1973) was highly significant (Mann-Whitney U test, p<0.001). Consistent

with earlier results, densities in the upper creek (123 ± 112 trout/100 m) were significantly

higher (Mann-Whitney U test, p<0.001) than those in the lower creek (4 ± 9 trout/100 m), and

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average individual masses of juvenile steelhead in upper creek sections (75 ± 50 trout/kg) were

significantly lower (Mann-Whitney U test, p<0.001) than those in lower creek sections (15 ± 20

trout/kg). These results reaffirmed the drainage use pattern observed earlier where the upper

creek consistently provided suitable spawning and young-of-the-year rearing habitat, while the

lower creek supported only relatively few yearling and older juvenile steelhead/rainbow trout.

Overall, of the 1,172 trout sampled, 64% were <100 mm TL, only 8% were 100–200 mm TL,

and 28% were >200 mm TL.

Nelson (1994b) also presented the results of an exhaustive habitat typing effort made on

the creek during July–October 1993. No attempt will be made here to summarize the very

detailed reach-by-reach descriptions. The results clearly corroborate earlier, more qualitative

observations regarding overall habitat quality for steelhead spawning and rearing between the

upstream and downstream creek areas. Habitat quality in the lower creek was negatively

impacted by the proximate effects of cattle grazing, crop production, and urbanization, and the

diversion of water for both agricultural and domestic use. These effects included loss of riparian

vegetation, excessive erosion, increased sediment load, and reduction of instream flow which led

to extensive desiccation of the stream and lagoon. With little suitable spawning substrate,

minimal vegetative cover, poor pool development, and a lack of instream flow, there was little or

no successful spawning and little rearing in the lower creek, as evidenced in the electrofishing

survey. In contrast, as seen in previous surveys, there was greater diversity and complexity in

physical habitat in the upper creek, along with mostly perennial flow conditions. These high

quality habitat attributes continued to support adult spawning and year-round rearing habitat for

at least three year classes of juvenile steelhead and rainbow trout. Nelson’s (1994b) primary

recommendation was to maintain the favorable spawning and rearing habitats for steelhead in the

upper creek and to re-establish adequate flow conditions in the lower creek. The negative

impacts of the various land uses in the lower creek would then be secondarily addressed once

instream flow requirements were determined and implemented.

The juvenile steelhead population and stream habitat in Santa Rosa Creek were assessed

again in fall 1994 by Alley & Associates (1994). The study area extended from the fish ladder at

SKM 5.4 to SKM 20.9, and consisted of seven study reaches (1.3 ± 0.7 km long; range, 0.35–

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2.4 km) interrupted by one 6.3 km long dry section. Two reaches corresponded to the lower

creek area described by Bailey (1973), while five corresponded to the upper creek area. In

contrast to earlier population surveys at Santa Rosa Creek, study reaches were not selected

randomly but were instead selected to represent the portion of the stream providing highest

quality rearing habitat for juvenile steelhead. For example, the lowermost 5.4 km of stream

below the fish ladder was not included in the survey because “(s)ampling in previous years

indicated very low steelhead densities” in that section. Another departure from earlier

methodology was that abundance estimates were made on a mesohabitat-specific basis (i.e. pool,

riffle, run, etc.), and pools were sampled most comprehensively as they were the most heavily

utilized habitat type under the prevailing low-flow conditions. Abundance estimates were made

using the multiple-pass removal method, where habitat-type specific densities of each age class

were weighed by the cumulative length of each habitat type in each reach. As such, only one

comprehensive density estimate (no. trout/km) could be determined for each reach.

Comparison with earlier surveys, especially on a stream-wide basis, was compromised in

that the study design used by Alley & Associates (1994) lacked replication of randomly-selected

sections within reaches, and sampling was biased toward higher density reaches and mesohabitat

types. Yet, an attempt is made below to present the results within the context of the earlier, more

similarly designed studies.

Alley & Associates (1994) determined that reach densities averaged 1,737 ± 582

trout/km (range, 1,299–2,669 trout/km) and although this average was on the same order of

magnitude as that seen by Bailey (1973; 3,580 ± 2,192 trout/km), it was still significantly lower

(Mann-Whitney U test, p ≈ 0.03). Densities in the upper creek (1,892 ± 634 trout/km) tended to

be higher than those in the lower creek (1,351 ± 74 trout/km) but, contrary to previous studies,

this difference was not significant (Mann-Whitney U test, p>0.12). When the data of Alley &

Associates (1994) are plotted along with those of Knable (1978) and Nelson (1994b), depicting

the results of all three fall population surveys (Figure X), it becomes apparent that spawning and

subsequent rearing have been most heavily concentrated in the upper creek area. Alley &

Associates’ (1994) density estimates for the two lower creek reaches appear anomalous relative

to Knable (1978) and Nelson (1994b), and are likely a result of the bias introduced in the

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selection of reaches and individual habitat units sampled, as described above and further in their

report. Based on observed densities of juvenile steelhead in fall 1994, Alley & Associates

(1994) estimated the corresponding number of adult steelhead that would be produced at 405

fish, using a model developed by Kelley et al. (1987). Alley & Associates (1994) concluded that

low stream flow in summer was the factor that most limited the number of juvenile steelhead in

Santa Rosa Creek, by rendering step-run and glide habitats unuseable and by reducing the

amount of escape cover in pools.

Overall, the most noticeable change that has occurred in this drainage is the pattern of use

by steelhead, as reflected in the results of the similarly designed studies of Bailey (1973), Knable

(1978), and Nelson (1994b). Using average densities of juvenile steelhead in the upper and

lower creek areas as an indication, the percentage of the population using the upper creek has

increased from about 73% in 1970, to 87% in 1978, to 97% in 1993, corresponding to a decrease

in the lower creek from 27% to 13% to 3%, respectively. This change in frequencies in use

between the two stream areas over this 23 yr period was highly significant (Χ² = 38.8, df = 2, p =

0.0001). These results strongly suggest that the degraded physical habitat and reduced instream

flows in the lower creek have progressively rendered this area less and less suitable for steelhead

production.

Toro Creek Drainage Toro Creek, a tributary to Estero Bay, has historically supported a steelhead population.

When surveyed by the CDFG in the mid-1930’s, spawning grounds were noted as common

along the stream. No diversions or barriers were observed. Toro Creek was otherwise described

as “a small brushy stream (that) contains a ‘goodly’ number of small fish because of the shade

and pools”. Apparently juvenile steelhead did not reach a large size in the creek, which would

suggest that they smolted and emigrated at an early age and small size. Angling pressure was

reportedly heavy in spring, and then light during May–July. Because of low flow conditions late

in the season and a prevailing dry cycle, Toro Creek was not highly regarded for its summer

trout fishing. The surveyors recommended that only a few steelhead be stocked in wet years.

Early stocking records showed that the Toro Creek steelhead population had been supplemented

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with 10,000 juveniles in 1932 and 8,000 in 1933.

The CDFG surveyed the lowermost 16 km of Toro Creek on 17 January 1962. The upper

8 km of the survey area contained the high-gradient headwater and canyon sections of the

stream, while the lower 8 km of stream flowed through a low-gradient coastal valley developed

for agriculture. Spawning areas were scarce in the headwaters where much of the rubble and

gravel were cemented by calcareous deposits, but abundant and of high quality throughout the

lowermost 8 km of stream. Rearing conditions for juvenile steelhead were poor because of

extremely low flow conditions. Under normal flow conditions, rearing habitat in the form of

pools and cover was of high quality, especially in the canyon section. Although there were no

natural migration barriers in the stream, there was a flashboard dam in the headwaters which

blocked adult steelhead migration. One domestic diversion was seen in the headwaters, and

many pump diversions for irrigation in the lower creek section. No pollution was seen in the

headwater or canyon sections, but in the lower section, grazing cattle polluted the stream with

sediment and excrement. The lagoon area was polluted with an oily-brine outfall from the

Standard Oil Company’s El Estero pumping station. No juvenile steelhead/rainbow trout were

seen in the lower creek section, and only a few in the canyon section. Low trout abundance was

attributed to several years of persistently low flow conditions resulting from drought,

exacerbated by agricultural diversions. Local residents reported good adult steelhead runs in

past years, including fish that reached the absolute headwaters during the 1957-58 season.

Angling pressure was probably only heavy at the stream mouth during steelhead season when the

adults were running. The surveyors regarded Toro Creek as a steelhead production area with

high potential. They also recognized that increased pumping for irrigation would lower

steelhead production.

Toro Creek was surveyed in its entirety by the CDFG during the weeks of 25 June and 2

July 1973. The uppermost 4 km of the headwaters were dry, although they were included in

addition to the upper and lower 8 km sections described in the 1962 CDFG survey. Suitable

spawning areas occurred not only in the lowermost 8 km as in 1962, but also in the uppermost 4

km headwater section. Spawning areas were described as both readily accessible and of very

high quality. Rearing habitat in the form of pools and cover was especially good in the canyon

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section, although some pool habitat was also available in the lower section. There were no

barriers to migrating adult steelhead. Two diversions were observed. Juvenile steelhead

abundance was estimated at seven stations throughout the survey area, by use of electrofishing

and the two-pass removal method. Trout were found at all but one station. The expanded

estimate for the 16 km of wetted stream was about 16,000 trout, 6.5–25.5 cm in length. The

relatively large juvenile population was attributed to observed high quality habitat conditions,

including an abundance of aquatic insect prey. The adult steelhead run supported a popular sport

fishery. A local resident reported that no stocking had occurred during the previous 15–18 yrs,

and that at least three spawners migrated successfully past SKM 16 the previous winter where

five redds had also been observed.

The CDFG monitored for adult steelhead at Toro Creek on seven occasions from 14

January–7 April 1974 (M. Seefeldt, CDFG, unpubl. field reports of 14 January–7 April 1974).

No adults were seen on the first occasion, although there has been substantial rainfall and the

sandbar at the creek mouth had been breached for more than a week. A total of 10 adult

steelhead was captured by electrofishing from the second occasion on 10 February 1974 through

the final occasion. These fish averaged 50.1 ± 5.9 cm FL (range, 41.9–61.6 cm FL). Many

juvenile steelhead/rainbow trout were observed during these surveys; these fish ranged in length

from about 10 to 35.5 cm.

In fall 1974, the CDFG investigated the juvenile steelhead population in Toro Creek

(Snider 1974). The character of the upper and lower 8 km sections of the creek was apparently

the same as described in the 1962 CDFG survey (see above). The area of primary concern was

the lowermost 3.2 km of the stream, where Standard Oil proposed an expansion of their onshore

oil storage facility. Juvenile steelhead abundances were determined in 12 randomly-selected

30.5 m sections by use of electrofishing and the two-pass removal method. For comparison,

juvenile steelhead abundances were also determined in six randomly-selected 30.5 m sections by

the same method in the upper 8 km section.

Mean estimated juvenile density in the lower creek was 30 ± 3 trout/100 m, which gave

an estimate of about 2,400 trout for the entire lower 8 km section. Mean density in the upper

creek was an order of magnitude higher, 390 ± 128 trout/100 m, and corresponded to about

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31,200 trout for the entire upper 8 km section. Age 0+ trout averaged about 80 mm TL, age 1+

about 157 mm TL, and age 2+ about 227 mm TL. In the lower creek, 14% of sampled trout were

age 0+, 69% were age 1+, and 17% were age 2+, while corresponding figures in the upper creek

were 78%, 17%, and 5%, respectively. Overall, 68% of the juvenile steelhead population were

young-of-the-year, 26% were 1+, and 6% were 2+. Based on age-class specific survival rates

from Shapovalov and Taft (1954), observed juvenile production in Toro Creek corresponded to

an estimated adult steelhead production of about 1,400 fish. Snider (1974) related the relatively

large steelhead run at Toro Creek to the lack of development in the drainage.

Barclay (1975) found juvenile steelhead/rainbow trout in Toro Creek, and “they were

abundant in areas with clean, cool waters that flowed over gravel or other rock substrate.”

The CDFG surveyed Toro Creek in its entirety during 11–15 September 1978. Of its 30

seasonal tributaries and springs, 11 contributed significant flow to the creek. The distribution

and quality of spawning and rearing habitats were essentially the same as described in the 1973

CDFG survey (see above). A heavy concentration of spawning reportedly occurred at about

SKM 14.5 the previous winter. Juvenile steelhead/rainbow trout were observed from SKM 6

through SKM 15. The greatest density and largest individuals were associated with the high

quality rearing habitat in the canyon section. Angling pressure was light, and the 1976–77

drought apparently had a noticeable, negative impact on the juvenile population (see Knable

1978, below). One diversion was observed, although it was not in operation. There was a

potential barrier to adult immigration at a culverted road crossing in SKM 11. Localized heavy

grazing pressure, especially in the lower section, resulted in removal of riparian vegetation and

fecal pollution. The creek was also polluted with urban debris.

During 17 August–22 October 1978, Knable (1978) estimated juvenile steelhead

abundance and biomass in Toro Creek and five other San Luis Obispo County coastal streams.

Toro Creek was selected to represent a steelhead production system subject to a moderate level

of human-induced degradation. Abundance and biomass were estimated using electrofishing and

the two-pass removal method in six randomly-selected, 30.5 m long sections, in three 1.6 km

long stream reaches. Two reaches occurred in the lower 8 km section, while a third was in the

upper 8 km section; the stream was dry above this point.

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Mean estimated juvenile density in the lower creek was 3 ± 5 trout/100 m which was an

order of magnitude lower than that seen by Snider (1974); mean upper creek density was 7 ± 8

trout/100 m, two orders of magnitude lower than that seen by Snider (1974). There was no

significant difference between lower and upper creek densities (Mann-Whitney U test, p>0.18).

Observations indicated that greatest trout abundance was in SKM 8.0–9.7, but this reach was not

sampled. Apparently, juvenile recruitment in 1978 was poor as only 7% of sampled trout (n =

28) were likely young-of-the-year (50 –99 mm in length), 75% were 100–199 mm, and 18%

were 200–299 mm. Most sampled trout were yearlings as average individual mass was 38.5 g.

Knable (1978) concluded that the lower section of Toro Creek was evolving toward a

state of advanced degradation, primarily because of grazing effects on riparian vegetation and

water quality as described in the 1978 CDFG survey (see above). In the upper 8 km section, two

flashboard dams, a short channelized section, and a natural 1.2 m waterfall were noted but not as

significant problems for steelhead production. The exception was the road crossing with blocked

culverts in SKM 11 mentioned above.

Steelhead were still mentioned as a viable fishery resource in Toro Creek in recent

(through 1988) CDFG file documents, in connection with proposed development. Adult

steelhead have reportedly been seen in Toro Creek as recently as the late 1980’s (D. W. Alley,

D. W. Alley and Associates, pers. comm. of 21 January 1993).

Villa Creek Drainage Little documentation was found regarding the history of steelhead in Villa Creek, a small

tributary to northern Estero Bay. When surveyed by the CDFG during 13–14 August 1969,

stream flow was interrupted along its entire course of about 13 km. There were suitable

spawning areas in the central and upper stream, given winter flow conditions. Suitable rearing

habitat occurred in the upper 5 km of stream where pools had sufficient cover; pools in the lower

8 km were silted and lacked cover. There were two low-flow barriers in the upper 5 km; both

were considered passable under winter flow conditions. Juvenile steelhead/rainbow trout were

found from 1.6 km above the mouth to the headwaters, including above the barriers. Visually

estimated densities of 6.5–10.0 cm long trout were about 490 trout/100 m in SKM 1.6–8.0, and

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about 220 trout/100 m in the uppermost 5 km. The population supported a winter fishery at the

creek mouth for adult steelhead with moderate to heavy pressure. Summer fishing for juveniles

was light because of restricted access to private lands.

In 1980, the CDFG determined the abundance of juvenile steelhead/rainbow trout by

electrofishing at three stations on the uppermost 3.2 km of Villa Creek (P. P. Chappell, CDFG,

unpubl. memo. of 14 October 1980). The exact date of sampling was not indicated but it is

assumed that sampling occurred sometime during late summer–early fall. There was an average

of 392 ± 124 trout/100 m. The uppermost 5 km appeared to provide most of the spawning and

rearing habitat in the stream, although this conclusion was based on limited observation.

SANTA BARBARA COUNTY

Arroyo Hondo Drainage

Canada del Corral Drainage No formal records of an historical steelhead population were found for Canada del

Corral. However, this small stream did receive CDFG plants of juvenile steelhead rescued from

the Santa Ynez River during the 1940’s. In addition, documents contained in the CDFG file

expressed concern for the steelhead resource in this creek in relation to pollution from oil

extraction operations in the lower stream area.

Cañada Honda Creek Drainage No information was discovered regarding an historical steelhead population in Cañada

Honda Creek, which is contained within the boundaries of Vandenburg Air Force Base.

However, in a brief survey conducted recently by the CDFG, the stream appeared highly suitable

as a steelhead and/or resident rainbow trout production area; no apparent migration barriers

existed at the Highway 1 or Southern Pacific railroad crossings, and the physical instream habitat

and riparian vegetation provided favorable spawning and rearing conditions. A local authority

indicated that much of the creek was dry during the 1987–92 drought except for isolated pools,

and it was concluded that an electrofishing survey should be conducted to assess the trout

population (S. Parmenter, CDFG, pers. comm. of 31 March 1993).

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Carpinteria Creek Drainage No information was discovered regarding steelhead in Carpinteria Creek. However, the

following Carpinteria tributaries, which apparently comprise trout habitat, have received CDFG

plants of O. mykiss: Dark Canyon Creek was stocked with 3,000 juvenile steelhead rescued from

Santa Cruz Creek in the Santa Ynez River system in 1939; Deer Creek has received hatchery

rainbow trout; and Gobernador Creek was planted with juvenile steelhead rescued from the

Santa Ynez River in 1939, and has received hatchery rainbow trout.

Dos Pueblos Canyon Creek Drainage No record of steelhead was found for Dos Pueblo Canyon Creek. However, the creek

apparently comprises O. mykiss habitat as it has received CDFG plants of hatchery rainbow

trout.

Gaviota Creek (Cañada de la Gaviota) Drainage There is little formal record regarding the steelhead in Gaviota Creek. In the report of a

mid-1930’s CDFG stream survey, it was mentioned that steelhead entered the creek in winter.

Steelhead have continued to run in Gaviota Creek (Swift et al. 1993), at least as recently as 1986

(S. Sasaki, CDFG, unpubl. file report of 3 October 1986). Adult steelhead were reported, nearly

annually, attempting to ascend the stream at the Gaviota State Park road crossing. Sasaki had

also observed and sampled juvenile steelhead and/or rainbow trout in sections of the creek

adjacent to Highway 101. The creek still had perennial flow, and spawning areas and rearing

pools were available to steelhead. Sasaki predicted that run sizes were very small. The 1987–92

drought may have had a significant negative impact on this small population, as Nehlsen et al.

(1991) listed the native Gaviota steelhead stock as extinct. No steelhead were captured when a

30 m section, downstream from a Highway 101 grade stabilization structure, was electrofished

during 21–23 January 1992 (D. McEwan, CDFG, unpubl. memo. of 26 March 1992).

The Gaviota Creek tributary, Canada de las Cruces, was planted with juvenile steelhead

rescued from the Santa Ynez River in 1939.

Mission Creek Drainage

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No detailed records of an historical steelhead run were found for Mission Creek.

According to Cooper et al. (1986), it is probable that steelhead more fully exploited the Mission

Creek system and other small Santa Barbara County coastal streams before dams were built by

Spanish colonists. Steelhead still attempt to ascend these streams; one was caught in lower

Mission Creek in the late 1950’s (Cooper et al. 1986). Swift et al. (1993) indicated that

steelhead have continued to run in Mission Creek in recent years. Juvenile steelhead were

present in the stream in 1984 (Santa Barbara News-Press of 3 June 1984). Habitat loss and

migration barriers, both as a result of flood control structures, and reductions in water quality

and quantity have probably contributed to the decline of the Mission Creek steelhead population.

Rattlesnake Creek

Resident rainbow trout are present in Rattlesnake Creek, a Mission Creek tributary to

which steelhead may have had access at one time. Cooper et al. (1986) presented a detailed

description of this stream. Local residents claim that Rattlesnake Creek has historically

supported a native rainbow trout population. The CDFG stocked 1,000 juvenile rainbow trout

into the creek in 1975. Natural propagation does occur as young-of-the-year have been

observed. The size of the population is highly variable and probably regulated by density-

independent factors such as floods and droughts. For example, trout density decreased in a 1.3

km reach from >31 trout/km in 1982 to 1.5 trout/km in 1984. Although no details were given on

the structure of the population, rainbow trout used in field experiments have ranged from 10.2 to

32.5 cm TL (Cooper 1984).

Refugio Creek (Canada del Refugio) Drainage Although Refugio Creek is a known steelhead stream, no details were found regarding

the history of its population. The creek received plants of juvenile steelhead rescued from the

Santa Ynez River during the 1940’s, and hatchery rainbow trout. CDFG file documents made

reference to observations of adult steelhead ascending the stream in winter to spawn, especially

in “wet years”. Steelhead presence in the stream was documented as late as 1958. Man-made

structures in the lower creek area, including a low water crossing built in the 1960’s, have

created barriers for immigrating adult steelhead. A description of Refugio Creek is presented by

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Fox (1975; as cited in Hemphill and Cooper 1983). The current status of the steelhead

population is not known.

Rincon Creek Drainage, Including Portions in Ventura County Although known historically as a steelhead stream, few details were discovered regarding

the steelhead in Rincon Creek. When surveyed by the CDFG in 1934, the creek had recovered

from an input of sediment that resulted from an earlier fire in the watershed. The upper

watershed was described as not being prone to erosion. It was also indicated that local anglers

did not value the steelhead runs, as the fish “would return to the sea”. The creek received plants

of juvenile steelhead rescued from the Santa Ynez River during the 1940’s, and hatchery-reared

rainbow trout.

Within the lower creek area, rubble drop structures on two bridges and a long, inclined

concrete culvert at the U.S. 101 crossing effectively prevent immigration of steelhead from the

ocean (M. H. Capelli, California Coastal Commission, unpubl. project review of 22 March 1989

to C. Cesena, Caltrans). The input of fine sediment from agricultural operations has also

degraded the stream below the confluence with Casitas Creek. Yet, the headwaters still maintain

perennial flow and other habitat attributes necessary for successful spawning and rearing of

steelhead. Nehlsen et al. (1991) listed the Rincon Creek steelhead stock as extinct. It is not

known if resident rainbow trout remain in the headwaters.

San Antonio Creek Drainage No information was discovered regarding an historical steelhead population in San

Antonio Creek. However, the creek did receive a plant of juvenile steelhead rescued from the

Santa Ynez River in 1944. Warmwater fishes and stickleback apparently inhabit this stream,

based on information contained in the CDFG file. The CDFG recently made a casual survey of

general conditions in the lower creek, and concluded that the observed low gradient and soft-

sediment substrate did not give the stream a high priority status for further investigation with

regard to steelhead assessment and restoration (S. Parmenter, CDFG, pers. comm. of 31 March

1993).

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San Jose Creek Drainage San Jose Creek received a plant of juvenile steelhead rescued from the Santa Ynez River

in 1944, and has also been stocked with hatchery rainbow trout. A 3.2 kg steelhead was caught

in the creek in 1975. The lowermost portion of San Jose Creek is channelized with a concrete

lining for flood control. This structure may function as a migration barrier because it lacks

resting areas for immigrating adult steelhead.

Atascadero Creek

Swift et al. (1993) indicated that steelhead have continued to run in the San Jose Creek

tributary, Atascadero Creek, in recent years. Two adult steelhead were captured in the

Atascadero Creek tributary, Maria Ygnacio Creek, in March 1982 (Santa Barbara News-Press of

23 March 1982). These fish measured 76 cm, 4.5 kg and 69 cm, 2.5 kg. A dense growth of

emergent vegetation in Atascadero Creek, at the confluence with the Maria Ygnacio, may create

a barrier to upstream migrating adult steelhead (M. Cardenas, CDFG, pers. comm. of 22 April

1993).

Santa Maria River Drainage, Including Portions in San Luis Obispo and Ventura Counties

Shapovalov (1944b) described the Santa Maria River drainage, and its steelhead

population and fishery, through 1944. The Santa Maria is formed by the confluence of the

Cuyama and Sisquoc rivers, about 40 km upstream from the river mouth. Stream flow in most of

the drainage was intermittent or interrupted each year, especially during the dry summer season.

Some headwater tributaries of the Sisquoc River, such as Manzana Creek and its tributaries, and

the South Fork Sisquoc River, maintained perennial flow over long stream reaches. Other

streams, such as the Cuyama River tributary, Kelly Canyon Creek, had perennial pools in their

upper reaches. In addition to natural drought conditions, stream flow was reduced by

groundwater extraction for agriculture, especially in the Santa Maria and upper Cuyama valleys,

and by several surface water diversions. Forest fires, especially during the preceding 22 years,

had removed ground cover and increased erosion. Consequently, runoff occurred more rapidly

during the wet season, and less water was available for stream flow during the summer as more

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of it was absorbed in the stream bed where the eroded materials were deposited. No dams were

present in the system as of 1944.

In addition to the migratory steelhead, resident rainbow trout were also present in the

drainage, especially in headwater areas (Shapovalov 1944b). The resident rainbows probably

comprised indigenous populations, progeny of introduced hatchery fish, and hybrids of the

various genotypes.

Steelhead used the Santa Maria River primarily as a migration corridor to and from the

Cuyama and Sisquoc rivers, where reproduction and nursery areas existed. Adult steelhead

entered the river following the first heavy rains of the wet season (Shapovalov 1944b). The

greatest proportion of the run entered during December–March. No estimate of run sizes was

available. Few details were known about spawning area locations, although the Sisquoc system

was apparently used more heavily by steelhead than the Cuyama system (see below). The

Sisquoc tributary, La Brea Creek, was known as a reproduction area for steelhead. In general,

spawning and rearing conditions had greatly deteriorated as a result of the aforementioned forest

fires; sediment had smothered spawning gravels and filled rearing pools. Prior to the fires, some

Sisquoc River tributaries were famous for their steelhead and rainbow trout fishing.

Hatchery-reared steelhead and rainbow trout were stocked in the Sisquoc River, and in

tributaries to both the Sisquoc and Cuyama, at least as early as 1930–33 (Shapovalov 1944b).

No records were found for stocking which may have occurred before 1930. Juvenile steelhead

rescued from the Santa Ynez River were planted in the Santa Maria system during 1940–44;

more may have been planted in 1945 and 1946, the last years of fish rescues in the Santa Ynez,

but no records were found. Stocking details for which documentation was found are given

below.

As of 1950, there appeared to have been no adult steelhead fishery for 10–15 years in the

Santa Maria River, and very few steelhead were reported to have entered the Cuyama River for a

decade (W. A. Evans, CDFG, file letter regarding the proposed Vaquero Dam project on the

Cuyama River). Most steelhead entered the Sisquoc River system and spawned in the

headwaters. Juvenile steelhead/rainbow trout measuring 23–36 cm were reportedly abundant in

the inaccessible tributaries of the Sisquoc in years following large steelhead runs. The last

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sizeable steelhead run in the Santa Maria system occurred in 1941, few entered in 1942 and 1943

during brief periods when river flow reached the ocean, and no runs were thought to have

occurred during the ensuing 7 years of drought. In addition to the naturally inconsistent flows in

the Santa Maria River, completion of the Vaquero Dam project in the late 1950’s made flow

conditions for steelhead even more unreliable. Vaquero Dam, which creates Twitchell

Reservoir, is located on the Cuyama River about 11 km upstream from the confluence with the

Sisquoc River. The dam was built for flood control and replenishment of ground water in the

Santa Maria Valley.

Steelhead use of the Santa Maria River system has not been assessed recently. Steelhead

may still have access to the Sisquoc system when flow conditions allow, but extensive habitat

degradation throughout the system, and lack of access to the upper Cuyama River (see below),

greatly limit steelhead use.

Cuyama River and tributaries

Virtually no details were discovered regarding the historic steelhead resource in the

Cuyama River. Steelhead migrations to and from most of the Cuyama system became obstructed

when Vaquero Dam was completed in the lower river in the late 1950’s. It can be assumed that

the opportunity for steelhead to use the Cuyama River was gone by 1960.

The Cuyama River tributary, Alamos Creek (San Luis Obispo County), was planted with

a total of 28,000 juvenile steelhead rescued from the Santa Ynez River during 1940–42

(Shapovalov 1944b), and has also been stocked with hatchery rainbow trout. The creek has

perennial stream flow and now runs into one of the main arms of Twitchell Reservoir.

The Cuyama tributary, Kelly Canyon Creek, was planted with 6,000 hatchery rainbow

trout in 1932 (Shapovalov 1944b). The creek’s watershed was destroyed by forest fires during

the 1920’s.

The following are headwater tributaries to the Cuyama River in Ventura County that

have been managed for catchable trout fisheries and stocked with hatchery rainbow trout but

whose CDFG files lack any mention or record of an historical steelhead run: Alamo Creek, with

a stocking record back to 1947; Beartrap Creek with a stocking record back to 1944 and 1947;

Reyes Creek with stocking records dating back to 1933 and 1941–48, and with wild juvenile

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rainbows observed in 1949.

Sisquoc River and tributaries

In addition to having been an important spawning and rearing area for Santa Maria River

steelhead, the Sisquoc River has also been managed for a resident rainbow trout fishery.

Documented CDFG plants of hatchery-reared rainbow trout date back to 1932 (8,000 fish), 1939,

and 1944–47. Some 20,000 hatchery-reared steelhead were also planted in 1930.

In the CDFG files, pools in the main stem Sisquoc River were noted as providing good

habitat for rainbows up to 36 cm which were well-fed on chubs (Gila sp.). In a 1959 CDFG

stream survey (W. M. Richardson, CDFG, unpubl. file report), a self-sustaining rainbow trout

population was found with all size-classes present ranging from young-of-the-year to adults 34

cm in length. A high abundance of chubs was also noted. Thus, the Sisquoc River still provided

a functioning system for natural production of O. mykiss, although there was no mention of a

contemporary steelhead run. A similar survey was conducted in August 1964 but under low

flow conditions (M. J. Whalls, CDFG, unpubl. memo.). Several size-classes of naturally

propagated rainbow trout were still present although in lower abundance than in 1959 due to

poor water conditions. It was also mentioned that upstream movement of anadromous fishes in

the Santa Maria system had been all but eliminated because of intensified water use. In a CDFG

survey in the lower Sisquoc River in April 1984, rainbow trout were reportedly common with

several size-classes present (S. Sasaki, CDFG, unpubl. memo.).

The Sisquoc tributary, La Brea Creek, was a known spawning area for steelhead

(Shapovalov 1944b). The creek was also a famous fishing stream before forest fires in the

1920’s destroyed the watershed. Eroded materials were washed into the stream over the years,

and by the time of a mid-1930’s CDFG survey, sediment covered the spawning gravels and filled

the pools. La Brea Creek was stocked with 6,000 hatchery rainbow trout in 1932.

The Manzana Creek drainage, in the headwaters of the Sisquoc, had perennial flow,

unlike most portions of the Santa Maria system (Shapovalov 1944b). CDFG stocking records for

Manzana Creek date back to 1930 when 15,000 hatchery-reared steelhead were planted. Some

10,000 hatchery rainbow trout were also planted in 1930, and about 4,500 during 1941–42. The

creek also received a total of 47,240 juvenile steelhead rescued from the Santa Ynez River

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during 1940–44. The Manzana tributary, Davy Brown Canyon Creek, received about 1,900

hatchery rainbow trout during 1941–42, and 103,600 Santa Ynez steelhead during 1940–44. In

June 1956, CDFG personnel found a high abundance of 15–20 cm rainbow trout in Manzana

Creek.

The South Fork Sisquoc River received a plant of 10,000 hatchery-reared steelhead in

1933, and 3,200 hatchery rainbow trout in 1942 (Shapovalov 1944b).

The Sisquoc River tributary, Tepusquet Creek, was planted with a total of 73,800

juvenile steelhead rescued from the Santa Ynez River during 1940–44 (Shapovalov 1944b). The

creek has also been stocked with hatchery rainbow trout.

Santa Ynez River Drainage The Santa Ynez River probably supported the largest steelhead run in southern

California, and was famous for its steelhead sport fishery (e.g. Mears 1947). In an early account,

Holden (1910) related the popularity of the lower Santa Ynez for catching steelhead as large as 9

kg, and how these fish would ascend the stream 65–80 km to spawn in the upper drainage where

resident rainbow trout were also abundant (see also Fry 1938).

Gibraltar Dam, located about 116 km upstream from the river mouth and built in 1920,

was the first man-made obstruction to block steelhead access to the upper Santa Ynez drainage.

Landlocked steelhead, 13–39 cm long and 2–4 years old, were captured when Curtis (1937) gill-

netted Gibraltar Reservoir in November 1937. These fish included females with developing ova.

No young-of-the-year steelhead were observed in the reservoir. In the tributary streams above

the reservoir, Curtis (1937) identified suitable spawning grounds in the Santa Ynez River below

the confluence with Mono Creek; in Mono Creek up to the debris dam; and in Gidney Creek.

Although no juveniles were observed in the Santa Ynez or Mono Creek, both reportedly received

spawning runs of steelhead. Spawning reportedly occurred in February, although the 1937

spawning run was apparently small. Siltation and desiccation were mentioned as potential

problems for successful spawning in Mono Creek and the upper Santa Ynez River. Gidney

Creek was unsilted and contained surficial flow later into the season. Camuesa Creek was

apparently not used by steelhead spawners for some unknown reason.

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In addition to supporting landlocked steelhead native to the drainage, the Gibraltar

Reservoir stock was also supplemented with 25,000 hatchery-reared steelhead in 1932; 87,000 in

1933; 30,000 in 1934; 50,000 in 1935; and 40,000 in 1936. Some 10,000 hatchery rainbow trout

were stocked in 1932. Shapovalov (1944a) also indicated that 9,000 juvenile steelhead, rescued

from the Santa Ynez River, were stocked in the reservoir in 1939, 195,000 in 1940, and 25,440

in 1944.

During the mid-1930’s, the CDFG conducted a cursory survey of 120 km of the Santa

Ynez River to evaluate the system’s suitability for stocking of hatchery-reared trout. The survey

report indicated that spawning grounds for steelhead and rainbow trout were common along the

entire stream, but that flow was a limiting factor for spawning habitat quantity. During spring

freshets, steelhead were observed spawning in all tributaries and in the mainstem river below

Gibraltar Dam. Natural propagation produced the principle supply of harvestable juvenile

steelhead and rainbow trout in the stream. Planting was not recommended for the river or

tributaries because of high mortality due to intermittent flow conditions in summer. Fish rescues

were conducted every summer and fish losses were typically heavy after 1 June.

Shapovalov (1944a) described the Santa Ynez River drainage, and its steelhead

population and fishery, through 1944. Tributary streams typically went dry in their lower

reaches during the summer, but maintained perennial flow or series of pools in their upper

reaches. Much of the main stem Santa Ynez below Gibraltar Reservoir also became desiccated

during May–July, except for several kilometers of stream in the vicinity of Solvang; at the

lagoon, which was also several kilometers long (see Shapovalov 1940b); and occasionally at

large pools elsewhere. Stream flow during the dry season in the lower Santa Ynez had been

reduced by the effects of forest fires, water storage and diversion in the upper drainage at

Gibraltar Reservoir and Jameson Lake, and groundwater pumping for irrigation. There was a

saltwater intrusion barrier near the mouth of the Santa Ynez River which included a reportedly

satisfactory fishway. Yet, despite unstable flow conditions, water discharges at Lompoc on the

lower Santa Ynez during 1928–44, were great enough to allow immigration of adult steelhead to

upstream spawning grounds in all years except probably 1929 and 1931, which were very dry

(Moffett and Nielson 1945).

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Steelhead, most of which entered the river during December–March following the first

heavy rains of the season, still spawned as far upstream as Gibraltar Dam. Landlocked

steelhead, and possibly various strains of rainbow trout and hybrids of the different genotypes,

persisted in Gibraltar Reservoir and in the creeks upstream from there. Steelhead progeny,

which were rescued annually from the drying Santa Ynez below Gibraltar Dam, were planted in

creeks both above and below the dam. No counts were ever made of the adult steelhead run in

the Santa Ynez, but as Shapovalov (1944a) indicated, the 1,036,980 juvenile steelhead rescued

from the drying main stem in 1944 suggested a very large run. This count would serve as the

basis for an underestimate of the adult run size as an additional proportion of the juvenile

population went uncounted: fish which migrated to the lagoon before rescues began, those which

survived in the remaining live portions of the river system, and those which presumably died in

the desiccated lower reaches of tributaries. A local CDFG employee believed that the 1943-44

adult steelhead run in the Santa Ynez at least equalled the 1938-39 and 1939-40 runs at Benbow

Dam on the South Fork Eel River in northern California, which he had personally observed.

Adult steelhead runs at Benbow Dam had ranged from 12,995 to 25,032 fish from 1938-39 to

1943-44. Forest fires during the preceding 20 years had reduced steelhead/rainbow trout

populations, especially above Gibraltar Reservoir, either by direct mortality or through the

destruction of spawning and rearing habitat by erosion and siltation. Among the upper

tributaries affected were Alamar, Indian, and Buckhorn creeks where trout had survived the

summer dry season in perennial pools.

Shapovalov (1944a) reported that, at that time, most mainstem spawning by steelhead

occurred upstream from Buellton to Gibraltar Dam. Steelhead also spawned in nearly all

accessible tributaries below the dam, including Alisal, Santa Cota, Cachuma, Tequepis Canyon,

and Santa Cruz creeks. Alamar and Indian creeks were among the tributaries above Gibraltar

Reservoir which were known to have been utilized by steelhead before the dam was constructed

(see also the above summary of Curtis 1937).

Fish rescue operations were conducted by the CDFG each summer for several years in

the Santa Ynez drainage below Gibraltar Dam. No records were available prior to 1939, but

during 1939–44 (excluding 1941 when sufficient flow persisted), a total of about 2,850,000

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juvenile steelhead was rescued from the lower mainstem Santa Ynez River (Shapovalov 1944a).

The fish ranged in batch sizes from about 212 to 1,411 fish/kg (nearly all rescued steelhead were

young-of-the-year). On average, about 73% of each year’s rescue was replanted in perennial

water within the Santa Ynez River system, the majority in the lagoon (see below). In addition, a

combined total of about 1,450,000 juvenile steelhead was rescued in 1945 and 1946; no rescues

were conducted after 1946 due to a lack of fish (CDFG, unpubl. file data; see also below). As an

example of the magnitude of juvenile steelhead production in the Santa Ynez River, Shapovalov

(1944a) presented approximate numbers of steelhead rescued from three river reaches in 1944;

corresponding densities were 11,298, 32,219, and 51,781 steelhead/km. That nearly all rescued

steelhead were young-of-the-year indicates that main stem Santa Ynez steelhead smolted and

emigrated to the ocean primarily at age 1.

During 1940–1947, nearly 2,550,000 juvenile steelhead were planted in the lower Santa

Ynez River, primarily in the lagoon and in perennial water at Solvang (Shapovalov 1944a;

CDFG, unpubl. file data). With the exception of 1947, these fish were rescued steelhead from

within the Santa Ynez River drainage. In addition, a total of 133,000 hatchery-reared juvenile

steelhead were planted in the Santa Ynez River during 1930–35 (Shapovalov 1944a). Some

5,000 hatchery-reared rainbow trout were stocked in the river in 1930 (Shapovalov 1944a), 650

in the lower river in 1945, and 35,160 in the lower river during 1950–53 (CDFG, unpubl. file

data).

On 28–29 March 1946, a party of state and federal fishery biologists conducted a visual

survey of steelhead spawning in the Santa Ynez River (L. Shapovalov, CDFG, unpubl. field

correspondence of 2 April 1946). In addition to observations of recently completed redds, adult

steelhead were seen moving upstream and actually spawning among four river locations from

Alisal Creek to Oso Canyon, where high quality spawning grounds occurred. In contrast, no live

steelhead or spawning activity were observed from the saltwater intrusion barrier near the river

mouth to the Highway 150 crossing at Lompoc. The substrate in this river reach was dominated

by shifting silt, sand, and fine gravel. Shapovalov concluded that spawning habitat quality for

steelhead was very poor from the mouth to the Salsipuedes Creek confluence, of doubtful quality

from Salsipuedes Creek to Solvang (a conservative judgement since no observations were

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documented for this reach), and excellent from Solvang to Gibraltar Dam. He also noted that

high quality spawning grounds existed in tributaries but that the flow in these streams was too

low at the time of the survey to allow the ascent of adult steelhead. Finally, many adult

steelhead carcasses were observed in the lower river between the mouth and Lompoc; apparently

high adult mortality had occurred in this area during the previous 2 weeks when water

temperature peaked at ≥ 21° C.

The winter of 1946-47 was relatively poor for steelhead due to little precipitation and low

flow. There was no steelhead run in the fall of 1951 (W. A. Evans, CDFG, unpubl. field notes).

Cachuma Dam, known now as Bradbury Dam which creates Lake Cachuma about 76 km

upstream from the river mouth, was completed in early 1953. The last substantial steelhead run

occurred in 1945-46 (H. L. Lantis, CDFG, unpubl. file letter). In 1946-47, large numbers of

steelhead were observed outside the mouth of the river, waiting for the sandbar to breach to

make their ascent. This never occurred due to lack of precipitation and consequently there was

no spawning run that year. Observations or catches of steelhead in the Santa Ynez after 1946

were relatively rare. For example, about 25 fish were taken in the river in 1952. Adult steelhead

were otherwise taken by anglers in the ocean surf near the river mouth during 1947–52; too little

freshwater outflow prevented these fish from entering the river system. Juvenile steelhead had

been planted in the lagoon in an effort to reestablish the run, but low precipitation and reduced

river outflow due to Bradbury Dam were cited as causes for the failure of these plantings. Some

20–40 adult steelhead, reportedly up to 5.5–6.5 kg, were observed at the head of the Santa Ynez

lagoon in March 1956. Steelhead were also observed in the lower Santa Ynez tributary,

Salsipuedes Creek. Some steelhead were also reportedly taken in the river during the spring of

1962.

Lake Cachuma has been heavily stocked with hatchery-reared rainbow trout. The CDFG

stocked the reservoir with 199,250 rainbow trout fingerlings (Arrowhead, Hot Creek, and Mt.

Shasta strains @ 55–317/kg) from 24 February 1953 through 16 October 1953 in preparation for

the 1 May 1954 opening of angling at the reservoir (CDFG, unpubl. file data). Some 10,271

catchable-sized rainbow trout (@ about 11/kg) from a private hatchery were stocked on 6 August

1954, under purchase by the County of Santa Barbara (S. M. Soule, CDFG, unpubl. intraoffice

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correspondence of 7 October 1954). The CDFG planted an additional 2,277,767 fingerlings

during 1954–1958 but, overall, survival and thus creel returns were low because of poor water

quality for trout in summer. Fingerling plants were discontinued in 1959, and the management

recommendation of stocking only catchable-size rainbow trout during cool-water months (H. L.

Huddle, CDFG, unpubl. file report of 23 October 1958) has been followed since 1960. The

extent to which these planted trout disperse up- and downstream in the system, and the effect

they may have on native steelhead and rainbow trout, is not known.

No wild rainbow trout were found in the Santa Ynez River between Lake Cachuma and

Gibraltar Reservoir during a survey in November 1972 (S. Sasaki, CDFG, unpubl. memo.).

Steelhead were reportedly caught in the lower Santa Ynez during 1972-73, a high water year,

although these catches were unverified (S. Sasaki, CDFG, unpubl. memo.).

By 1975, Bradbury Dam had all but eliminated the Santa Ynez steelhead run from its

estimated average annual size of 20,000 migrant adults, as reported by the CDFG (California

Department of Fish and Game 1975). Insufficient water releases from Lake Cachuma, to provide

flow for migrations, spawning, and rearing, and a lack of adult steelhead salvage facilities at the

dam, were cited as the primary causes for the demise of the run.

In 1986, the CDFG indicated that excellent spawning areas still existed in the main stem

Santa Ynez below Bradbury Dam (S. Sasaki, CDFG, unpubl. file report of 3 October 1986).

However, it was also indicated that even in years of high rainfall when adults could conceivably

enter the river and spawn, flow below the dam would not be maintained through the summer and

fall to allow for juvenile survival.

In 1989, the California Sportfishing Protection Alliance (CSPA) submitted a petition to

the California Fish and Game Commission to list the Santa Ynez River steelhead as an

endangered species under the California Endangered Species Act (R. J. Baiocchi, CSPA, petition

of 25 August 1989). The basic tenet of the petition was that the Santa Ynez steelhead was

unique because of the maximum size of 9 kg attained by adults, and because of the size of the

estimated average adult run, which historically was on the order of 20,000 fish. The CDFG

rejected the petition based on the conclusion that these characteristics were not uncommon in

California steelhead populations (P. Bontadelli, CDFG, unpubl. memo. of 7 December 1989).

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See “Discussion” for more on this issue.

Nehlsen at al. (1991) listed the Santa Ynez River steelhead stock as being at a high risk

of extinction.

Santa Ynez River Lagoon. During late spring and summer 1940, the CDFG rescued

more than 525,000 young steelhead from the drying Santa Ynez River (Shapovalov 1940b).

Nearly all of these fish were young-of-the-year, and 191,700 were planted in the Santa Ynez

River lagoon. One lot of about 8,700 steelhead was retained at the Fillmore Hatchery in Ventura

County, to be used in a lagoon stocking experiment and in brackish water challenge tests. The

steelhead were marked by clipping both ventral fins, and reared through September 1940. On 5

October 1940, when the fish had reached an average size of nearly 9 cm and 9 g, the young

steelhead were planted in the freshwater portion of the Santa Ynez lagoon, apparently with

success as no signs of stress or mortality were seen over the next several hours of observation. A

short-term experiment had also been made at the hatchery on 26 September 1940 of transferring

small samples of marked steelhead (3 and 12 fish in two trials) from fresh hatchery water to

brackish lagoon water and back to fresh water. The fish in both trials showed no signs of stress.

The combined results of both experiments suggested that young steelhead could be planted

directly in brackish water lagoons from fresh water with little or no mortality.

Hundreds of thousands of juvenile steelhead rescued from the Santa Ynez River were

planted in the lagoon during 1940–1947 (see above). In February 1954, 16,500 catchable

rainbow trout were planted in the lagoon with apparently poor returns to the creel (H. L. Huddle,

CDFG, unpubl.intraoffice correspondence of 3 December 1957). During 17–18 June 1954, the

CDFG seined both shallow (1 haul) and deep water (4 hauls) habitat in the lagoon to cursorily

evaluate the retention of these rainbow trout (P. E. Giguere, CDFG, unpubl. intraoffice

correspondence of 9 July 1954). Several marine and euryhaline fishes were captured but no

rainbow trout or juvenile steelhead. However, one each hatchery rainbow trout (26.0 cm) and

juvenile steelhead (15.0 cm) were seined from small freshwater pools upstream from the

saltwater intrusion barrier. On 14 July 1954, two rainbow trout (~17.0–18.0 cm) were seined

from the most seaward extension of the lagoon but not at any of three other lagoon stations

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(CDFG, unpubl. field report of 14 July 1954).

During 12–13 March 1958, one group of 10 of each 7.5–10.0 cm long and 20.0–23.0 cm

long hatchery rainbow trout were placed in live cages at two lagoon locations where surface

salinity ranged from 2.5 to 4.0 ppt (H. L. Huddle, CDFG, unpubl. intraoffice correspondence of

21 March 1958). All trout survived after 24 h, as had rainbow trout fingerlings tested at 12 ppt

salinity in aquaria. These results seemed to corroborate the results of Shapovalov’s (1940b)

seawater challenge tests, as reported above.

Agua Caliente Creek

Although no historical record was discovered, steelhead probably spawned in Agua

Caliente Creek prior to the construction of Gibraltar Dam, as they did in other tributaries in the

upper Santa Ynez River drainage. Agua Caliente Reservoir, created by a debris dam completed

on the creek in 1937, was planted with 13,000 juvenile steelhead rescued from the Santa Ynez in

1939, and 27,000 in 1940 (Shapovalov 1944a). The reservoir basin was completely filled with

sediment by 1944.

Alisal Creek

Alisal Creek, which enters the Santa Ynez below Bradbury Dam, has been used

historically for spawning by steelhead (Shapovalov 1944a). Some 26,000 juvenile steelhead

were rescued from the creek in 1940. An adult O. mykiss about 38 cm in length, which was

presumably a steelhead, was captured in the creek by an angler during the 1992-93 steelhead

season (M. Cardenas, CDFG, pers. comm. of 5 April 1993).

Ballard Creek

Steelhead probably spawned in Ballard Creek, a Santa Ynez tributary below Bradbury

Dam, as they did in most accessible tributaries (Shapovalov 1944a). The creek received a plant

of 1,500 juvenile steelhead rescued from the Santa Ynez in 1943.

Cachuma Creek

Steelhead spawned in Cachuma Creek (Shapovalov 1944a), prior to the construction of

Bradbury Dam. The creek received a plant of 7,000 juvenile steelhead rescued from the Santa

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Ynez in 1942. Steelhead runs occurred at least as late as 1948, and the creek, which now flows

into one of the main arms of Lake Cachuma, has also historically contained resident rainbow

trout (CDFG, unpubl. file data).

Gidney Creek

Steelhead probably spawned in Gidney Creek prior to the construction of Gibraltar Dam;

it now flows into one of the main arms of Gibraltar Reservoir. Curtis (1937) identified favorable

spawning grounds in the creek, where juveniles (5–12.5 cm long) of landlocked steelhead from

the reservoir were seen at a density of about 30 trout/pool. Gidney Creek was unsilted and

contained surficial flow late into the season.

Hilton Canyon Creek

O. mykiss adults were observed spawning in Hilton Canyon Creek, the uppermost

tributary to the Santa Ynez below Bradbury Dam, during mid- to late February 1993 (C. Fusaro,

Santa Barbara City College, pers. comm. of 9 March 1993). One spawning pair comprised fish

which were 46–51 cm in length. Some 22 adult trout, at visually estimated weights of 1.8–2.7

kg, were observed in the creek on one day. It was not known if these fish were actual steelhead

or large rainbow trout which had moved downstream out of Lake Cachuma, although this

problem was being investigated. Adult fish continued to be observed in the creek through late

April 1993 (M. Cardenas, CDFG, pers. comm. of 22 April 1993).

Mono Creek and Tributaries

Steelhead spawned in Mono Creek, a tributary to the upper Santa Ynez, prior to the

construction of Gibraltar Dam. Curtis (1937) identified suitable steelhead spawning grounds in

Mono Creek up to the debris dam, and although no juveniles were observed, the creek reportedly

received spawning runs of landlocked steelhead from the reservoir. Siltation and desiccation

were mentioned as potential problems for successful spawning in the creek.

Sea-run steelhead also spawned in the Mono Creek tributaries, Alamar and Indian creeks,

before the dam was built (Shapovalov 1944a). Forest fires since the 1920’s had reduced O.

mykiss populations in these tributaries, and in the Indian Creek tributary, Buckhorn Creek, either

by direct mortality or through the destruction of spawning and rearing habitat by erosion and

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siltation. Trout had survived the summer dry season in perennial pools in these streams. Indian

Creek received a plant of juvenile steelhead rescued from the Santa Ynez in 1945.

Salsipuedes Creek and Tributaries

As of 1974 (P. R. Gantt, Goleta, CA, unpubl. correspondence in the CDFG file) and 1986

(S. Sasaki, CDFG, unpubl. file report of 3 October 1986), Salsipuedes Creek and its tributary, El

Jaro Creek, reportedly continued to support natural steelhead propagation. According to Sasaki,

the Salsipuedes, which enters the lower Santa Ynez River about 24 km above the mouth, had

suitable steelhead spawning areas, perennial flow, and an intact riparian canopy which sheltered

the stream. Although the presence of spawning adult steelhead had not been investigated, Sasaki

did observe many O. mykiss fingerlings in the creek in some of the 17 years he had worked in

the area.

Electrofishing surveys were conducted in Salsipuedes and El Jaro creeks in March 1987

and 1988 (Harper 1988), in which both juvenile and adult steelhead were observed. Four adult

trout were captured on 11 March 1987 in the lowermost 5 km of Salsipuedes Creek: (i) a 48 cm

FL female steelhead which was age 4+ and had spent 2 years each in fresh and marine water; (ii)

a 34.5 cm FL ripe male which could not be distinguished as a resident or migrant trout; (iii) a

30.5 cm FL female which appeared to be a migrant; and (iv) a 30 cm FL ripe male which could

not be distinguished as a resident or migrant trout. Another large trout, about the same size as

the 48 cm FL female steelhead above, was seen but not captured. Some 10–15 juvenile trout,

>10 cm FL, were also captured on this date. On 12 March 1987, two adult trout were captured in

El Jaro Creek: a 22.5 cm FL male which appeared to be a stream resident, and a 28.5 cm FL

female which appeared to be a migrant that had grown in the lagoon or ocean. On 17 March

1988, several juvenile trout about 16 cm in length were seen but not captured in lower

Salsipuedes Creek. On 31 March 1988, eight juvenile trout, 9.5–18.5 cm FL, were captured by

electrofishing; these fish appeared to be stream residents as they displayed no signs of smolting.

Thus, Salsipuedes Creek supported a small, self-sustaining O. mykiss population, which

appeared to include both steelhead and resident rainbow trout.

Several adult O. mykiss were reportedly caught by anglers in Salsipuedes Creek during

February–March 1993 following heavy precipitation (M. Cardenas, CDFG, pers. comm. of 5

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April 1993). The catches were to have included about a dozen 30 –33 cm fish, and about five

fish which were nearly 46 cm in length. These catches were not verified by the CDFG, however.

Santa Cota (Zanja de Cota) Creek

Santa Cota Creek, which enters the Santa Ynez below Bradbury Dam, has been used

historically for spawning by steelhead (Shapovalov 1944a). The creek was stocked with 10,000

hatchery-reared rainbow trout in 1932.

Santa Cruz Creek and Tributaries

Steelhead spawned in Santa Cruz Creek (Shapovalov 1944a) prior to the construction of

Bradbury Dam. The creek now flows into one of the main arms of Lake Cachuma. The creek

was planted with 10,000 hatchery-reared juvenile steelhead in 1932, and received 3,000

juveniles rescued from the Santa Ynez in 1939. Some 10,000 juvenile steelhead were rescued

from the creek in each of 1939 and 1940 (Shapovalov 1944a).

Steelhead could not access the Santa Cruz Creek tributary, Peach Tree Creek, because of

impassable waterfalls on Santa Cruz Creek. However, the creek received a total of nearly

125,000 juvenile steelhead rescued from the Santa Ynez River during 1939–44 (Shapovalov

1944a). There was no indication whether the plants were made to take advantage of a favorable

but inaccessible rearing area in Peach Tree Creek, or if the fish were to support summer trout

fishing there.

Tequepis Canyon Creek

Tequepis Canyon Creek was used historically by spawning steelhead, where 3,660

juveniles (@ 970 fish/kg) were rescued in May 1941 (Shapovalov 1944a). Steelhead access to

the creek is now blocked by Bradbury Dam.

Zaca Creek

No records were discovered of historical steelhead use of Zaca Creek, although the

stream was planted with juvenile steelhead rescued from the Santa Ynez River. This stream

enters the Santa Ynez downstream from Bradbury Dam.

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Tecolote Creek Drainage In a report to the CDFG, Gantt (1973) presented the efforts of a local property owners

association to restore the steelhead/rainbow trout resource of Tecolote Creek. Included in the

report appendix were photographs of juvenile steelhead/rainbow trout caught by anglers during

the 1930’s. Historically, steelhead had access to about the lowermost 10 km of the stream, at

which point a 6 m natural waterfall blocked upstream passage to the remaining 5 km of stream

contained within Los Padres National Forest. The original steelhead/rainbow trout population

was apparently decimated when early landowners pumped the creek dry.

As of 1973, two flood control dams, 1.8 m and 3.7 m in height, respectively, created

migration barriers downstream from the waterfall. A 23 m long, inclined concrete culvert was

also a potential barrier to upstream migration of steelhead under high flow conditions.

Otherwise, high quality spawning and rearing habitats existed along most of the stream.

Exceptions were a 1.6 km long section of the lower stream which had interrupted surficial flow

during the summer dry season, and another lower stream reach that was silted due to

construction activities and associated erosion. There was a small lagoon at the creek mouth, and

a sandbar often closed the stream during the summer.

No estimates were given regarding the size of historic steelhead runs or natural juvenile

population densities. As part of their restoration effort, the group represented by Gantt stocked

the creek with 4,200 juvenile steelhead and rainbow trout in mid-April 1973. The fish were

purchased from SilverKing Oceanic Farms in Santa Cruz County (see Waddell Creek). Some

3,900 of these fish were the progeny of wild Waddell Creek steelhead, while the remaining 300

were resident rainbow trout. The plant was made about 8 km upstream from the ocean, and most

fish were observed migrating toward the ocean within 2 weeks after release. About 700 were

rescued from pools in the interrupted flow section of the creek in July 1973, and released

downstream. Fish remaining in the stream apparently grew well. No follow-up documentation

on this operation was discovered in the CDFG files. The current status of this population is not

known, although groundwater extraction and surface diversions at Tecolote Creek after 1973, as

well as two drought periods, most likely depleted the stream flow, which would be predicted to

negatively impact the steelhead population.

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VENTURA COUNTY

Big Sycamore Canyon Creek Drainage Keegan (1990b) concluded that Big Sycamore Creek had a relatively low potential for

steelhead restoration because of a lack of perennial stream flow. Yet, Swift et al. (1993)

indicated that steelhead have run in Big Sycamore Canyon in recent years.

Calleguas Creek Drainage There is no formal record of steelhead inhabitation of this stream. A 1973 U. S. Fish and

Wildlife Service (USFWS) document stated that a proposed flood control project would have no

impact on fishery resources because the stream was intermittent and did not support fish

populations. Keegan (1990b) judged Calleguas Creek as having little potential for steelhead

restoration because of degraded habitat from sedimentation, and poor water quality from

agricultural runoff. The stream otherwise had a relatively constant stream flow, no known

barriers to fish passage, and an extensive and protected (Mugu) lagoon.

Arroyo Conejo Creek is an intermittent tributary to Calleguas Creek which contained no

salmonids in a 1948 CDFG survey.

Santa Clara River Drainage, Including Portions in Los Angeles County The Santa Clara River system once supported a popular winter steelhead sport fishery

based on its apparently “large and consistent runs” (Hubbs 1946; see also Kreider 1948). The

average annual run in the Santa Clara may have been on the order of about 9,000 adult steelhead

(Moore 1980a). Steelhead migrated upstream through the lower Santa Clara River to reach

spawning grounds in Santa Paula, Sespe, and Piru creeks, and perhaps in other tributaries and

reaches of the upper Santa Clara itself (see below). However, the steelhead stock has declined

precipitously since the mid-1950’s, primarily due to an increase in surface water diversion in the

lower Santa Clara by the United Water Conservation District. The unscreened diversion near

Saticoy has historically blocked upstream migration of adult steelhead, entrained emigrating

smolts into percolation basins, or eliminated fish movements to and from the ocean altogether by

dewatering the river channel during critical migration periods. The current diversion structure,

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the Vern Freeman Diversion Dam, was equipped with a fish ladder and intake screens in 1989 to

enhance fish passage, and the effectiveness of these features are being evaluated (ENTRIX

reports). The steelhead decline has also been attributed, in part, to altered flow patterns and

blocked access to historic spawning grounds by upstream dams (see below). Nehlsen et al.

(1991) listed the Santa Clara River steelhead stock as having a high risk of extinction.

The following is a chronological rundown of information from CDFG files regarding the

presence or stocking of steelhead and rainbow trout in the main stem Santa Clara River. Early

CDFG records showed that 5,000 juvenile steelhead were stocked in 1938 in the “River of

Doubt” area, and 21,600 were planted in the lagoon in 1944, the latter being steelhead which

were rescued from the Santa Ynez River. In a CDFG survey in the River of Doubt area in 1949,

no rainbow trout were found despite stocking of hatchery rainbows in 1939 and during 1942–48.

The main stem river was apparently not surveyed again for O. mykiss for many years. Bell

(1978) found no O. mykiss by seining in the main stem Santa Clara from its mouth, although

hatchery escapees of rainbow trout which live in the tailwater of the Fillmore Fish Hatchery

were observed. Areta and Willsrud (1980) also captured no O. mykiss by seining the main stem

during 8–24 May 1980. In both of these surveys, most of the fishes captured reflected an

assemblage of warmwater and euryhaline species.

In a two-year CDFG study of steelhead in the lower Santa Clara River system, Puckett

and Villa (1985) reported the steelhead captures presented in Table 3. In addition, 25 other O.

mykiss were captured during the study ranging in fork length from 20.3 to 45.7 cm, and in age

from 1 to 3 years old. Some of these fish may have been pre-smolted steelhead, and others

resident rainbow trout. No emigrating smolts were captured in a fyke net set in the Vern

Freeman Diversion canal at Saticoy during both years. Eleven other species of fish were

captured during the study, including both emigrating juvenile and spent adult Pacific lampreys

(Lampetra tridentata). Most adult lampreys were captured at the Sespe Creek weir although a

few were also caught at Saticoy. Puckett and Villa (1985) concluded that the lower Santa Clara

River served primarily as a migration corridor for both adult and juvenile steelhead, and was less

important as a spawning and rearing area, with the exception of the estuary as potential rearing

habitat. Fish movements, both upstream and downstream, were coincident with flow pulses

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following major storm events.

Piru Creek and Tributaries, including Portions of the Creek System in Los Angeles County

Piru Creek was historically a major steelhead spawning tributary in the Santa Clara River

system. Steelhead reportedly ascended Piru Creek occasionally as far as Buck and Snowy creeks

(W. A. Evans, CDFG, unpubl. field notes from 1946). However, since 1955, Santa Felicia Dam

at Lake Piru has blocked steelhead access to Piru Creek beyond the lowermost 9.7 km of the

stream. The dam at Pyramid Reservoir blocks fish migration further upstream as well.

Upstream portions of the stream are currently managed for both catchable and wild

rainbow trout fisheries (e.g. Deinstadt et al. 1990). Hatchery rainbow trout stocking records date

back to 1931. A mid-1930’s CDFG survey mentioned the presence of both rainbow trout and

juvenile steelhead. Some 5,000 juvenile steelhead were stocked in 1938, and an anecdote

indicated the presence of steelhead spawners in 1944–45 as far upstream as the Gold Hill area.

No trout were seen in the stream below Frenchman’s Flat in a 1946 survey, nor in a 1949

survey. Low summer flow and correspondingly high water temperature, and siltation were cited

as problems in the suitability of this section of Piru Creek as salmonid habitat. The exception

was some large, deep pools which held trout, such as in 1951 when several 31–36 cm rainbows

were observed. Bell (1978) found no O. mykiss in Piru Creek below Lake Piru during a seining

survey. However, this portion of the stream may have some potential as a steelhead spawning

and rearing area since a flow of 5 cfs is guaranteed below Santa Felicia Dam.

Agua Blanca Creek flows into Piru Creek upstream from Lake Piru. A mid-1930’s

CDFG survey indicated the presence of resident rainbow trout and juvenile steelhead, although

the stream was not considered a valuable resource because of low late-summer flows which

reduced available salmonid habitat. The stream had been stocked with 20,000 steelhead in each

of 1930 and 1931. There was no mention of steelhead in a 1949 survey, and few rainbow trout

were seen despite stocking in 1939, 1942, 1944, and 1946.

Buck Creek enters Piru Creek above Pyramid Reservoir. Steelhead apparently entered

this stream on occasion (W. A. Evans, CDFG, unpubl. field notes from 1946). It is a small,

intermittent tributary stream which has been stocked with hatchery rainbow trout at least as early

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as 1942.

Lockwood Creek is a headwater tributary to Piru Creek upstream from Pyramid

Reservoir with a record of presumably wild rainbow trout being present in 1946. These fish

could have also been juvenile steelhead although there is no mention of an historical steelhead

run. Seymour Creek is a tributary to Lockwood Creek for which stocking records of rainbow

trout date back to 1943–44. Catchable size trout were observed in the stream in 1946 but no

young-of-the-year.

Snowy Creek is a tributary to Piru Creek above Pyramid Reservoir which was apparently

used by steelhead on occasion (W. A. Evans, CDFG, unpubl. field notes from 1946). Rainbow

trout stocking records for this stream date back to 1942.

Santa Paula Creek and Tributaries

Santa Paula Creek is known historically as a major spawning tributary for Santa Clara

River steelhead, but there is no formal record on stock size. It is the first major tributary above

the Vern Freeman Diversion available to steelhead spawners returning from the Pacific Ocean.

About 6.4 km upstream from the confluence with the Santa Clara River, the Santa Paula

Diversion greatly reduces or eliminates stream flow below the dam during much of the year.

During periods of high runoff, steelhead may gain access to the base of the dam but lack of an

operable fishway blocks access to several (≥ 8) kilometers of suitable steelhead spawning habitat

upstream from the diversion.

Juvenile steelhead and rainbow trout were noted as being present in the stream in a mid-

1930’s CDFG survey. Since the 1940’s, Santa Paula Creek above the diversion has been

managed intensively as a catchable rainbow trout fishery, the activities of which included a

stocking and creel census experiment in 1947 (W. A. Evans, CDFG, unpubl. file report). The

presence of naturally propagated O. mykiss juveniles was noted during the experiment, and it

was indicated that these fish were probably the progeny of both resident rainbow trout and

steelhead. The steelhead population was supplemented with 5,000 juveniles in each of 1930 and

1931, 15,000 in 1938, and 3,500 in 1943. Stocking records for rainbow trout date back to 1930.

In March 1987, the USFWS conducted an electrofishing survey in Santa Paula Creek

below the diversion site which produced two adult steelhead (37.5 and 38.0 cm FL) and two

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adult resident rainbow trout (30.0 and 31.0 cm FL). These fish were captured in the pool at the

base of the diversion dam, which is where an angler had also caught two adult steelhead. In

addition, one 16.0 cm FL steelhead smolt was captured. The pool below the dam was also

electrofished in March 1988 and one, possibly two, adult steelhead was seen but not captured.

These surveys (B. Harper, USFWS, unpubl. file report) demonstrated that adult steelhead still

occurred in Santa Paula Creek but only in low numbers. Decimation of the population to this

level was primarily due to operational changes in the Vern Freeman Diversion, the inoperable

fishway at the Santa Paula Diversion, and drought. However, with the construction of fish

passage facilities at the Vern Freeman Diversion in 1989, the lower Santa Clara River should be

functional as a migration corridor for steelhead during periods of sufficient flow, and restoration

of the fishway at the Santa Paula Diversion would allow steelhead to take advantage of the

spawning and rearing habitat in upper Santa Paula Creek. The CDFG electrofished a 100 m

reach immediately below the Santa Paula Diversion Dam during 21–23 January 1992, but no

steelhead or rainbow trout were captured or observed (D. McEwan, CDFG, unpubl. memo. of 26

March 1992).

Sisar Canyon Creek is a headwater tributary to Santa Paula Creek. There was no mention

of steelhead using the stream historically via Santa Paula Creek although 5,000 steelhead (@

847/kg) were planted in the stream in 1938. Rainbow trout stocking records date back to 1939,

1943–47, and suitable spawning habitat and young-of-the-year O. mykiss were noted in a 1947

CDFG survey.

Sespe Creek and Tributaries

Sespe Creek is the only major steelhead spawning tributary in the Santa Clara River

system which remains unregulated. Access to the Sespe by steelhead spawners returning from

the Pacific Ocean has been impeded by the Vern Freeman Diversion in the lower Santa Clara

River (see main heading for Santa Clara River Drainage). There is no formal record of the

steelhead population size at Sespe Creek.

Much of the stream has been managed for a catchable rainbow trout fishery. Rainbow

trout stocking records date back to 1930–31, 1939, and 1942–48. A 40 km section of Sespe

Creek was added to the California Wild Trout Program in 1986, a measure which protects the

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stream’s free-flowing status.

The steelhead population was supplemented with 40,000 juveniles in 1930, 38,000 in

1931, and 20,000 in 1938. In 1944, 35,000 juvenile steelhead rescued from the Santa Ynez

River were planted in upper Sespe Creek.

Juvenile steelhead and rainbow trout were present during a mid-1930’s CDFG survey.

Juvenile steelhead were seen in the stream in 1937 although young-of-the-year were reportedly

rare. Steelhead were mentioned as being present in 1947. Juvenile rainbow trout or steelhead

(10–15 cm), but no young-of-the-year, were present in a 1949 CDFG survey. Steelhead

reportedly occurred in the upper Sespe during the winter of 1953–54.

Bell (1978) reported the presence of O. mykiss in the middle and upper Sespe during a

seining survey. Puckett and Villa (1985) reported small numbers of both juvenile and adult

steelhead captured during 1982–84, and a fair abundance of juvenile and adult Pacific lampreys

(see synopsis under the main heading for Santa Clara River Drainage). CDFG fish surveys,

conducted during 1983–86 in preparation of the Sespe Creek Wild Trout Management Plan, also

demonstrated the presence of wild rainbow trout (possibly including juvenile steelhead as well)

and juvenile Pacific lamprey (Sasaki 1986; S. Sasaki, CDFG, unpubl. file report). In both of

these cases, the presence of lampreys confirmed that anadromous fishes had access to Sespe

Creek via the lower Santa Clara River. No adult or juvenile steelhead were observed or captured

during a walk-through survey in April 1988 from Alder Creek to the West Fork Sespe Creek,

although several year classes of rainbow trout occurred in abundance including several fish ≥ 35

cm in length. Suitable steelhead spawning and rearing habitat was noted as being abundant, and

no barriers to adult migration were seen (M. Moore, Calif. Dept. Trans., unpubl. file report).

About 80 km of Sespe Creek remains available to steelhead for spawning and rearing.

Abadi Creek is a headwater tributary to Sespe Creek for which there are stocking records

for rainbow trout dating back to 1942 and 1946, but for which there is no record of an historical

steelhead run.

In the Sespe tributary, Bear Canyon Creek, juvenile steelhead and rainbow trout were

present during a mid-1930’s CDFG survey of this seasonal stream. Some 5,000 Mt. Whitney

steelhead (@ 847/kg) were stocked in the stream on 30 September 1938. Juvenile O. mykiss

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were observed in the stream in 1949.

Howard Creek is a seasonal tributary to Sespe Creek and in a mid-1930’s CDFG survey,

juvenile steelhead and resident rainbow trout were present. Steelhead use of the stream was

mentioned in field notes from 1949, and what were listed as 10–15 cm rainbow trout were seen

in the same year. Rainbow trout (15–25 cm) were seen in 1951. Howard Creek has been

managed primarily as a catchable rainbow trout stream. Stocking records date back to 1940,

1948, 1953, and 1956 for rainbow trout.

Rose Valley Creek is a seasonal tributary to Howard Creek. Although there is no explicit

mention of it in CDFG files, steelhead probably used this stream as they did Howard Creek.

Stocking records for rainbow trout date back to 1948. Dams have blocked steelhead access to

the upper portion of the stream since 1955.

Lion Canyon Creek is a tributary to Sespe Creek. In mid-1930’s CDFG stream survey,

juvenile steelhead and resident rainbow trout were listed as present. After this time, the stream

was managed primarily for a catchable trout fishery with rainbow trout stocking records dating

back to 1948. Juvenile O. mykiss were seen in the stream in 1949. Stream flow accelerators

were constructed in 1956 to increase pool habitat.

Lords Creek is a tributary to Sespe Creek. Stocking records for fingerling rainbow trout

date back to 1945 and 1947, but there was no mention in the CDFG file of steelhead in this

stream.

Piedra Blanca Creek is a tributary stream located in the upper Sespe drainage. Stream

flow in the Piedra Blanca is intermittent after late spring. Some 5,000 steelhead (@ 847/kg)

were stocked into the stream in 1938, but there was no mention in the CDFG file about an

historical steelhead run. Rainbow trout stocking records date back to 1942 and 1945, and

presumably wild rainbows were observed in the stream in 1949 and 1963.

Pine Canyon Creek is a tributary to Sespe Creek which has been stocked with rainbow

trout since at least 1946. No record was discovered of steelhead use of this stream.

Tule Creek is a headwater tributary to Sespe Creek. In a mid-1930’s CDFG survey,

juvenile steelhead and resident rainbow trout were listed as present. Spawning habitat was noted

as being common but the stream was not considered to be of much value because of its seasonal

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flow. No formal record of steelhead use in this stream was discovered, although it was likely

when flow conditions were suitable. Rainbow trout stocking records date back to 1942.

Minor Mainstem Santa Clara River Tributaries

Lost Creek is a Santa Clara River tributary for which there is mention of steelhead. W.

A. Evans (CDFG, unpubl. field notes) wrote on 30 April 1947, “Steelhead enter this stream.”

Bell (1978) found no O. mykiss in Todd Barranca, a tributary to the main stem below Santa

Paula Creek, during a seining survey.

The following are other minor tributaries to the main stem Santa Clara River that have

been stocked with hatchery rainbow trout, but whose CDFG files lack any mention or record of

an historical steelhead run: Hopper Canyon Creek, for which there are rainbow trout stocking

records dating back to 1942, 1944, and 1946, and its tributary, Tom Creek, which was planted

with fingerling rainbow trout in 1946 and contained 10–15 cm trout in 1947; Pole Creek with

stocking records dating back to 1940 and 1941, and as recently as 1984 (both Hopper Canyon

and Pole Creek are southward flowing streams which enter the Santa Clara between Sespe and

Piru creeks); and Willard Creek where 10 cm rainbow trout were seen in 1949 but no natural

propagation was thought to have occurred.

Santa Clara River Headwater Tributaries in Los Angeles County

CDFG records show that hatchery rainbow trout were stocked and present in the upper

sections of Bouquet Canyon Creek during the 1940’s and 1950’s, but there was no mention of an

historical steelhead run. The dam creating Bouquet Reservoir would now block steelhead access

to the most upstream portion of this stream.

Bell (1978) found no O. mykiss in Castaic Creek below Castaic Lake during a seining

survey.

No O. mykiss were seen in Elizabeth Lake Canyon Creek in a 1948 CDFG survey, and

there was no mention of an historical steelhead run. Steelhead access to the upper portion of this

stream would now be blocked by the dam at Castaic Lake.

Fish Canyon Creek is a tributary to Castaic Creek, above Castaic Lake. This is a highly

intermittent stream for which there are hatchery rainbow trout stocking records dating back to

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1945 and 1948. There is no mention of an historical steelhead run in the CDFG file. Steelhead

access to this stream would now be blocked by the dam at Castaic Lake.

San Francisquito Canyon and Soledad Canyon creeks are two streams for which there are

CDFG records for rainbow trout presence and/or stocking dating back to c. 1930, but for which

there is no mention of historical steelhead runs. Bell (1978) found no O. mykiss in these streams

during a seining survey.

Ventura River Drainage An excellent account on the history of the Ventura River and its steelhead fishery is

provided by Capelli (1974; see also Ventura County Fish and Game Commission 1973). The

Ventura River supported “large and consistent runs” of steelhead (Hubbs 1946) up until the late

1940’s when prolonged drought and the construction of Matilija Dam (completed in 1948) on

Matilija Creek decimated the population. Apparently, up until this time, steelhead weighing 3 to

4 kg were commonly taken by anglers.

In a 1934 CDFG survey, steelhead and resident rainbow trout were listed as present in the

river system. At this time, the river below the mouth of Matilija Creek, where diversions greatly

reduced stream flow, was considered to be of no value except during the winter when steelhead

used the river as a migration corridor to reach the abundant spawning grounds upstream,

especially in Matilija Creek.

The steelhead population was supplemented with 40,000 juveniles in 1930, 34,000 in

1931, and 15,000 in 1938. About 27,200 juvenile steelhead rescued from the Santa Ynez River

were planted in the Ventura in 1943, about 20,800 in 1944, and about 45,440 in 1945. Stocking

records for rainbow trout date back to 1936 and 1939.

CDFG personnel in 1946 (D. A. Clanton and J. W. Jarvis, CDFG, unpubl. file report of 8

May 1946) estimated that in normal water years, a minimum of 4,000–5,000 adult steelhead

spawned in the Ventura River system, about half of them in Matilija Creek. The observation of

several hundred yearling steelhead, 10–15 cm in length, in Matilija Creek was also noted in this

report.

In March 1947 under drought conditions, an estimated 250–300 adult steelhead were

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observed in scattered pools from the river mouth to the Foster Park bridge located about 5 miles

upstream (W. A. Evans, CDFG, unpubl. file report of 29 March 1947). The steelhead averaged

about 61–66 cm in length and 2–3 kg. Several adult steelhead which had become stranded in

shallow water and died were also noted. Redds were observed within this reach and it was

estimated that 3.2 km of available spawning habitat below the Foster Park bridge would support

a maximum of 1,000 steelhead spawners. Under these low flow conditions, upstream movement

of adults was impeded by a sandbar at the river mouth and several shallow riffles upstream. The

City of Ventura diversion dam above the Foster Park bridge blocked any further upstream

movement under low flow conditions. Yearling steelhead juveniles (23–25 cm in length) were

seen in the lagoon and in most pools observed.

A few steelhead reportedly entered the river in April 1950. No significant steelhead run

was reported again until January and February of 1953 when anglers reported the capture of

several individuals ranging in length from about 30–56 cm. Scales from the largest of these, a

female, showed that this fish had spent 3 years in fresh water and its last year in the ocean.

According to local fishermen, 1955 was the most productive steelhead season on the Ventura

River between the late 1940’s and 1973 (Ventura County Fish and Game Commission 1973). In

February and March 1958, anglers reported the presence of adult steelhead in the Ventura River

and two of its tributaries, Coyote Creek and Matilija Creek. However, a CDFG seining survey in

August 1958 in the river and tributaries including San Antonio Creek produced no young-of-the-

year steelhead. The apparent lack of spawning success was attributed to siltation problems in

Coyote Creek and the Ventura River due to construction of Casitas Dam on Coyote Creek, and a

general lack of suitable spawning grounds in San Antonio Creek. With completion of Casitas

Dam and the Robles Diversion Dam in 1958, the latter of which transfers water from the Ventura

River via the Robles-Casitas Canal for storage in Casitas Reservoir, flow conditions favorable

for Ventura River steelhead would become even more infrequent. In addition, both of these

structures were built without fish passage facilities.

In the early 1970’s, an organized effort was begun to promote the restoration of the

Ventura River and its steelhead population (Ventura County Fish and Game Commission 1973).

The Ventura County Fish and Game Commission’s proposal called for an end to pollution and

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development within the river and its floodplain, and for an increase in both quantity and quality

of instream flows to maintain aquatic resources.

Despite rather tenuous conditions for Ventura River steelhead following the construction

of dams and diversions and other development during the 1940’s and 1950’s, local anglers

continued to report the capture of small numbers of steelhead nearly annually into the early

1970’s (Ventura County Fish and Game Commission 1973), and thereafter based on a variety of

accounts in the CDFG file which included information on steelhead and resident rainbow trout

captures in the lower Ventura River and San Antonio Creek during March and October 1974,

February–April 1975, November–December 1978, and January 1979.

A number of minor studies has been conducted over the years to evaluate water quality in

the lower Ventura River as a component of the steelhead and resident rainbow trout habitat, and

to determine the status of the steelhead population. In August 1976, the CDFG conducted a

bioassay to determine acute impacts of effluent from the Oak View Sanitary District Treatment

Plant on rainbow trout. High mortality rates of rainbow trout suggested that water quality was

negatively impacted by the effluent for several kilometers downstream from the point of

discharge. Trout losses were associated with low dissolved oxygen concentrations, and high

ammonia and residual chlorine concentrations.

Based on the results of a field study conducted during the winter of 1976-77 near Casitas

Springs (Tippets 1979; Kelley 1982), it was concluded that a small remnant steelhead run existed

in the lower Ventura River; the size of the run was limited by the number of smolt-sized fish

remaining at the end of the first year; and the run size could only be enhanced if water quality

downstream from the Oak View Sanitary District Treatment Plant was improved. Densities of

rainbow trout and/or steelhead in five river reaches near Casitas Springs in December 1976

ranged from 249 to 1,262/ha. No adult steelhead were observed in this study, probably due to

extremely low freshwater outflow conditions which would block upstream migration. However,

run size was estimated to average about 100 adults.

The condition of the river and status of the steelhead population it supports remain

essentially the same at present. Nehlsen at al. (1991) listed the Ventura River steelhead stock as

being at a high risk of extinction. The 1987–92 drought was probably unfavorable for the

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steelhead, both in terms of pre-smolt survival in the stream, and in terms of allowing upstream

migration of adult spawners returning from the Pacific Ocean. Ventura River tributaries which

still produce steelhead are San Antonio Creek, which has about 19 km of habitat, and Coyote

Creek below Lake Casitas (Minutes of southern California steelhead meeting, USFWS, Ventura,

CA, 22 January 1991). Observations of small numbers of steelhead annually have continued,

including the sighting of between 14 and 25 adults on 5 May 1991 in the upper Ventura River

Estuary (R. A. Leidy, Wetlands Science and Field Program Manager, EPA, unpubl. memo. of 8

May 1991). The range of estimated total lengths of these fish was 350–625 mm. A short (≈ 15

m) section was electrofished at the SP Milling gravel extraction site during 21–23 January 1992;

this brief survey produced no steelhead or resident rainbow trout (D. McEwan, CDFG, unpubl.

memo. of 26 March 1992). However, heavy rains in early February 1992 should have created a

good opportunity for any remnant of the stock, as well as steelhead from other stocks, to enter

the river and spawn. The lagoon remained open to the Pacific Ocean in early June 1992 (M.

Capelli, California Coastal Commission, pers. comm.). The most recent documented sighting of

steelhead in the Ventura River occurred on 4 January 1993 when two adults, both about 51 cm in

length and between 2.3 and 2.7 kg, were observed beneath the Shell Road bridge, which is

located about 4.8 km above the estuary (M. Bennett, Oak View, CA, unpubl. letter of 7 January

1993 to M. Cardenas, CDFG). These fish had apparently entered the river following heavy

rainfall.

Coyote Creek and Tributaries

A CDFG stream survey from the mid-1930’s states that both resident rainbow trout and

juvenile steelhead were present in Coyote Creek at that time. The natural stocks of resident

rainbows and steelhead had been supplemented with hatchery plants, and were doing well prior

to a 1932 fire in the area. Coyote Creek was still identified as a steelhead stream in 1946 (D. A.

Clanton and J. W. Jarvis, CDFG, unpubl. file report of 8 May 1946), and it was indicated that

juvenile steelhead were rescued in the lower portion of the creek in dry years. In another 1946

report, CDFG personnel estimated that the 1945 steelhead run in the Coyote–Santa Ana Creek

system comprised at least 2,500 adults, and that the average was about 3,000 in normal water

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years, which made steelhead use of these streams comparable to that in Matilija Creek (D. A.

Clanton and J. White, CDFG, unpubl. file report). Spawning habitat was listed as being poor

downstream from a proposed (El Rancho Cola) dam site, 4.8 km above the confluence with the

Ventura River. About 11 km of Coyote Creek and 6.4 km of Santa Ana Creek above Highway

150 comprised the spawning areas in this system. In 1951, the CDFG reported anecdotes which

stated that steelhead were seen as far upstream as the El Rancho Cola Dam site, and that the

creek was considered as one of the important remaining spawning tributaries for Ventura River

steelhead (W. A. Evans, CDFG, unpubl. file report). Casitas Dam, 10.5 km above the

confluence and completed in 1958, prevented any further steelhead access to suitable spawning

grounds in this stream, as the dam was built without a fish passage facility. Some steelhead

production continues to occur in Coyote Creek below Lake Casitas (Minutes of southern

California steelhead meeting, USFWS, Ventura, CA, 22 January 1991).

Matilija Creek and Tributaries

According to CDFG personnel in 1946, Matilija Creek comprised one of the most

productive spawning grounds for steelhead in the Ventura River system (D. A. Clanton and J. W.

Jarvis, CDFG, unpubl. file report of 8 May 1946). Its 19 km of spawning area made up about

one-half of the entire stream area of the Matilija-Ventura section. Completion of Matilija Dam

in 1948 blocked steelhead access to this important spawning and nursery area. A little used fish

passage facility built in 1947 was removed in 1965 in connection with dam modification work.

The Matilija Creek steelhead population was supplemented with 10,000 juveniles (@

847/kg) in 1938. In 1944, 53,000 juvenile steelhead rescued from the Santa Ynez River were

planted into the creek, and 21,120 in 1945. Records for rainbow trout plants date back to 1939

and 1942–48.

North Fork Matilija Creek and Tributaries

CDFG personnel in 1946 estimated that <2% of the Ventura River steelhead run used the

north fork for spawning, despite the removal of a waterfall 2 years earlier which added about 5.6

km of available stream (D. A. Clanton and J. W. Jarvis, CDFG, unpubl. file report of 8 May

1946). Low flows and a lack of suitable spawning habitat were cited as causes of low steelhead

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use. The steelhead population was supplemented with 10,000 juveniles (@ 847/kg) from Mt.

Whitney in 1938, 1,000 juveniles rescued from Santa Ana Creek in 1944, and 3,900 of

unspecified origin in 1954. Stocking records for catchable rainbow trout date back to 1939 and

1942–47. Stream improvement work, which consisted of the construction of 40 flow

constrictors, was carried out in 1955. Wild fingerling and sub-adult rainbow trout, as well as a

few recently planted catchables, were sampled and noted to be abundant during an electrofishing

survey on 16 April 1985 (S. Sasaki, CDFG, unpubl. memo.). Rainbow trout were also stocked in

the Upper North Fork Matilija Creek in 1948, and in Murietta Canyon Creek in 1942.

San Antonio Creek and Tributaries

No formal record was discovered of an historical steelhead run in San Antonio Creek,

although 525 rescued juvenile steelhead from Gridley Canyon Creek and 1,500 from Howard

Creek in Ventura County were planted in the stream in 1944. Rainbow trout stocking records

date back to the period 1943–47. O. mykiss of two size classes (15–20 cm and 30–40 cm) were

sampled in the lower creek in a January 1982 CDFG survey (S. Sasaki, CDFG, unpubl. file

report). There was no mention of resident rainbow trout or steelhead following surveys in the

lower creek in April 1984 and April 1985 (S. Sasaki, CDFG, unpubl. file reports). Yet, San

Antonio Creek, which has about 19 km of habitat, reportedly continues to function as a steelhead

production area (Minutes of southern California steelhead meeting, USFWS, Ventura, CA, 22

January 1991).

Lion Creek, a tributary to San Antonio Creek, was stocked with hatchery-reared

steelhead (5,000 @ 847/kg) and rainbow trout in 1938. No record was discovered of an

historical steelhead run in this intermittent stream. Steelhead access would now be blocked by a

dam on the stream, about 6–8 km east of Ojai, as mentioned in a 1949 CDFG field note.

Another tributary to San Antonio Creek, Senior Canyon Creek, was stocked with

hatchery rainbow trout at least as early as 1945.

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LOS ANGELES COUNTY

Arroyo Sequit Drainage Small runs of steelhead have reportedly occurred in the Arroyo Sequit historically. The

CDFG surveyed this stream in mid-November 1979 by use of electrofishing, in a reach

extending about 3.2 km upstream from Leo Carillo State Beach campground (D. P. Drake,

CDFG, unpubl. memo. of 4 February 1980). At that time, stream flow was intermittent, and

water temperature ranged from 14.5° C in shaded areas to 16.0° C in exposed areas. O. mykiss

was present ranging in length from 5 to 16.5 cm. The 5–7 cm trout were very abundant (>200 in

a 5 m3 pool).

Both juvenile and adult steelhead have been observed in recent years (Keegan 1990b; M.

Capelli, Friends of the Ventura River, pers. comm. in 1992). Several trout, about 33–41 cm in

length, were observed in an upstream reach in November 1992 (M. Cardenas, CDFG, pers.

comm. of 30 March 1993). Based on their size and the fact that the creek mouth was not open to

the ocean, these fish were probably steelhead that were trapped in the creek from the previous

spawning season. Also, a very high density of young-of-the-year was observed. The watershed

appeared to be in good condition. No stocking records were discovered for the stream, so the

stock may be relatively unaffected genetically by introduced hatchery trout.

Five trout, 19.5–29.5 cm TL, were captured in the Arroyo Sequit by use of electrofishing

on 9 April 1993 (M. Cardenas, CDFG, pers. comm. of 22 April 1993).

Keegan (1990b) concluded that the steelhead run in the Arroyo Sequit Creek would be

enhanced with increased stream flow and improvements for fish passage. Apparently, a notch

has now been cut into a small check dam which will enhance fish passage to and from upstream

areas (M. Capelli, Calif. Coastal Comm., pers. comm.).

Los Angeles River Drainage No formal record of an historical steelhead run was found for the Los Angeles River,

although steelhead apparently did occur here once because Nehlsen et al. (1991) listed this native

stock as being extinct. No steelhead were observed in a CDFG survey in the upper Los Angeles

River in 1945, nor during an overnight set of a 30 m gill net and three minnow traps by CDFG

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biologists on 13–14 February 1975 in the river near Western Avenue (V. C. Bleich, CDFG,

unpubl. memo. of 14 February 1975). In the latter case, the only capture was three specimens of

bigmouth buffalo (Ictiobus cyprinellus), an introduced species to California which is generally

not associated with steelhead waters (see Moyle 1976). Steelhead access and use of the Los

Angeles River is precluded by the presence of flood control structures throughout much of the

lower river course, such as a concrete lining of the river channel and the dam at the Sepulveda

Flood Control Basin.

Arroyo Seco Creek and Tributaries

Arroyo Seco Creek, a tributary to the Los Angeles River, is managed for rainbow trout,

and is stocked with catchables although wild trout are apparently also present. CDFG records

dating back to c. 1941 mention nothing about a previous steelhead run. Tributaries to the Arroyo

Seco which also contain rainbow trout are Bear Canyon Creek and Little Bear Creek.

Big Tujunga Creek and Tributaries

Big Tujunga Creek is a major tributary to the Los Angeles River that originates in the

San Gabriel Mountains. No historical record or mention of steelhead was discovered for the

creek. However, early CDFG records showed that rainbow trout were planted in this stream

during 1942–46, as they were in the Big Tujunga tributaries, Mill Creek and Trail Canyon Creek.

Upstream migration of steelhead into the Big Tujunga would now be blocked by dams at

Hansen Lake and Tujunga Reservoir.

Other Tributaries

In a 1948 survey by the CDFG, O. mykiss was not seen in the Rio Hondo River although

a tributary, Mission Creek, was stocked with rainbows during the 1940’s, as were other Los

Angeles River tributaries such as Murray Creek and Pacoima Canyon Creek. No mention of

historical steelhead runs was found for these streams.

Malibu Creek Drainage At present, Malibu Creek is the southernmost Pacific coast stream known to support a

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self-propagating run of steelhead. The 30 m tall Rindge Dam was built in 1924, thus blocking

upstream migration of steelhead spawners beyond 4.2 km above the stream mouth. Prior to this,

6.5 kg steelhead were reportedly caught as they migrated upstream to the lower reaches of Las

Virgenes Creek and Cold Creek to spawn. Since the late 1960’s, releases of treated wastewater

from the Tapia Water Reclamation Facility have maintained a perennial surface flow in Malibu

Creek, even during the May–October dry season (Edmondson 1991). Nehlsen et al. (1991) listed

the Malibu Creek steelhead stock as having a high risk of extinction.

CDFG records indicate that there was a relatively large steelhead run in 1947 when the

sandbar across the mouth of the stream was opened manually, and steelhead were still noticably

present in 1952, although no quantification of the runs was given in either case. No O. mykiss

were observed during CDFG surveys in June 1969 and August 1972, in the 10 km from Tapia

Park to the Pacific Ocean. However, local residents reportedly caught steelhead below Rindge

Dam in 1968, and found two steelhead which had washed ashore during a February 1969 storm.

In mid-November 1979, the CDFG electrofished a 183 m reach of the creek, about 2 km

upstream from the Pacific Coast Highway (D. P. Drake, CDFG, unpubl. memo. of 4 February

1980). Stream flow was low (0.9–1.5 m3/s), and water temperature varied between 15.0° and

17.5° C. Ten O. mykiss were captured ranging in length from 12.7 to 19.0 cm. Drake also

reportedly observed 61 adult steelhead just below Rindge Dam in 1980 (Manwaring and

Edmondson 1986). A 1.2 km reach of lower Malibu Creek above Cross Creek Bridge was

electrofished on 24 May 1985 (W. E. Tippets, Calif. Dept. Parks Recreation, unpubl. memo. of

29 May 1985). No O. mykiss were seen or captured, although several other fish species were

present.

The “Malibu Creek Steelhead Watch” (Manwaring and Edmondson 1986) was conducted

on Saturdays from 4 January 1986 to 19 April 1986. A total of about 158 salmonid observations

was made, comprised of counts in the following classifications: resident rainbow trout, fish with

parr marks, steelhead smolts, and steelhead adults. Among these, 26 observations were of smolts

which were seen from 8 March to 5 April 1986. Only one adult steelhead was observed, a spent

female captured on 23 March 1986, which measured 69 cm in fork length and weighed 3 kg.

The results of this study led to the protective angling regulations currently in effect on Malibu

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Creek.

Minor reconnaissance surveys have continued over the years. The following fish were

observed in late 1986–early 1987 as reported by Manwaring and Edmondson (1987): (i) A

female which measured 50 cm FL and weighed 2.35 kg was captured in a trap near Cross Creek

Road on 14 February 1987. A second female measuring about 61 cm was lost from the trap. (ii)

Three females measuring about 50 cm and 3 kg were captured on hook-and-line; two below

Rindge Dam in late December 1986, and one about 0.8 km below the dam on 28 February 1987.

(iii) Three mature O. mykiss males, 33 to 46 cm in length, were caught at Rindge Dam in mid-

December 1986. The CDFG and USFWS also electrofished the creek downstream from Rindge

Dam in April 1987, and although O. mykiss was apparently captured, the observed fish could not

be conclusively identified as steelhead (Fisheries Management Activities in CDFG Region 5 for

April 1987). The CDFG electrofished a 100 m reach immediately below Rindge Dam during

21–23 January 1992 (D. McEwan, CDFG, unpubl. memo. of 26 March 1992); several O. mykiss,

ranging in length from about 20 to 41 cm, were observed but not captured.

No formal records were discovered of hatchery rainbow trout stocking in Malibu Creek

below Rindge Dam, although hatchery rainbows were planted at Malibu Creek State Park in

1984, and evidently these plants are made regularly (Manwaring and Edmondson 1986).

Steelhead habitat availability and use has been evaluated in recent years. Franklin and

Dobush (1989) determined that about 504 m2 of spawning habitat was available in Malibu

Creek. The highest quality spawning habitat was located in narrow gorge sections between the

mouth of Cold Creek (above Rindge Dam) and 2.0 km below Rindge Dam. Nearly 5 km of

rearing habitat was available; the highest quality habitat was also located in narrow gorge

sections, both below Cold Creek and above Las Virgenes Creek. Thus, about 86% of available

spawning habitat, and 65% of rearing habitat was inaccessible to steelhead because of upstream

migration barriers which included: (i) Rindge Dam; (ii) a waterfall near the Malibu Canyon Road

tunnel; (iii) a concrete apron at the stream gage near Cold Creek; and (iv) a concrete road

crossing in Century Ranch State Park. Franklin and Dobush (1989) concluded that spawning

and rearing habitat would increase by 590% and 180%, respectively, if fish passage was

provided at these sites. Evaluations are currently underway regarding a fish passage facility at

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Rindge Dam.

In a companion study to that by Franklin and Dobush (1989), Keegan (1990a) evaluated

habitat use of juvenile steelhead in August 1989, from the mouth of Malibu Creek to Rindge

Dam. This 4.2 km study area was divided into an upper (0.8 km), middle (1.0 km), and lower

(1.2 km) reach. Juvenile steelhead were most abundant (22.4 trout/100 m) in the upper gorge

reach, which contained the highest quality spawning and rearing habitat below Rindge Dam, as

determined by Franklin and Dobush (1989). Steelhead abundance decreased in the middle (17.5

trout/100 m) and lower (3.5 trout/100 m) reaches where abundances of introduced warmwater

species increased. Steelhead use of pools (75% of 145 trout observed) was significantly greater

(Χ² = 7.507, DF = 2, p = 0.0234) than that of runs (25%). Three or more age-classes were

present: 0+, which were <10 cm; 1+, 10–18 cm; and 2+ and older, >18 cm. Age 1+ trout were

more abundant (44% of 145 trout observed) than 0+ (32%) or ≥ 2+ (24%) trout, although

differences in relative abundance among 0+ and 1+ trout may have primarily reflected

differences in relative year-class strength. These results demonstrated that (i) successful

reproduction had occurred in at least 3 consecutive years, despite low flow conditions; (ii)

juvenile steelhead distribution was linked to quality of spawning and rearing habitat; and (iii)

summer flow and water temperature conditions were acceptable for juvenile steelhead rearing. It

was concluded that steelhead production in the Malibu Creek drainage could be at least tripled if

passage was provided for spawning adults over Rindge Dam.

San Gabriel River Drainage The San Gabriel River system once supported steelhead although little historical

information was discovered. In a personal communication to Ewy (1945), Commissioner L. F.

Payne of the Los Angeles Branch of the CDFG stated that “steelhead run up the San Gabrial

River in December, January and February to spawn”. Steelhead were mentioned in connection

with San Jose Creek, a tributary to the lower main stem San Gabriel River. This perennial

foothill stream supported steelhead and other native fishes through at least the 1940’s–50’s (L.

Pardy, CDFG, unpubl. memo. of 13 December 1991). Nehlsen et al. (1991) listed the native San

Gabriel River steelhead stock as extinct.

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The San Gabriel River is highly urbanized in its lower reaches in the Los Angeles Basin,

and is impounded further upstream. The first major dams form Morris Reservoir followed by

San Gabriel Reservoir. The San Gabriel system, especially its tributaries both upstream and

downstream from these reservoirs, has been intensively managed for catchable trout fisheries

since the 1930–40’s, and more recently for wild trout as well (Deinstadt et al. 1990). The CDFG

files did contain considerable information on rainbow trout stocking and associated observations

dating back to c. 1930. This information is briefly summarized below to indicate the

approximate historical distribution of suitable habitat for steelhead/rainbow trout in the system.

Hatchery rainbow trout have been stocked in the main stem San Gabriel River below

Morris Reservoir with records dating back to 1930. A main stem tributary, Little Dalton Creek,

was stocked with rainbow trout in 1945. Fish Canyon Creek is a tributary to the San Gabriel

below Morris Reservoir. Wild rainbow trout were present in the headwaters of this stream

during CDFG surveys conducted in 1949, 1956, and 1973. Robert’s Canyon Creek is also

tributary to the main stem below Morris Reservoir. Rainbow trout were present here in a 1947

survey and into the 1950’s. Rainbow trout have occurred in San Dimas Canyon Creek, a main

stem tributary, as determined by CDFG surveys. Finally, rainbow trout have also been stocked

in Winter Creek, which flows into Big Santa Anita Canyon Creek, a tributary to the San Gabriel

River below Morris Reservoir.

The various forks of the San Gabriel River are located upstream from Morris and San

Gabriel reservoirs. The CDFG files contained information on rainbow trout presence and

stocking dating back to c. 1930, but lacked any record of historical (pre-reservoir) steelhead

runs, for the following San Gabriel forks and their tributaries. The East Fork San Gabriel River

and two tributaries, Cattle Canyon Creek and Devil’s Canyon Creek, have been stocked with

rainbow trout since at least 1930. Rainbows were observed in Cattle Canyon Creek during a

1933 CDFG survey. Coldwater Canyon Creek, a tributary to Cattle Canyon Creek, has also been

stocked with rainbows since 1930, and rainbows were present during a 1981 CDFG survey (D.

Drake, CDFG, unpubl. memo.).

The North Fork San Gabriel River and one of its tributaries, Soldier Creek, have also

contained resident rainbow trout since at least 1930. Rainbow trout were present in another

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tributary, Bichota Creek, during a 1949 CDFG survey, but not in Cedar Creek in a 1948 CDFG

survey.

The West Fork San Gabriel River has also contained and been stocked with resident

rainbow trout since at least 1930 (see also Deinstadt et al. 1990), as has Bear Creek. A tributary

to the latter, the West Fork Bear Creek, also contained resident rainbow trout when surveyed by

the CDFG in 1948. Below the falls in Chileno Creek, 5–15 cm rainbow trout have been

observed in high abundance by the CDFG. Rainbow trout were present in Devil’s Canyon Creek

during a 1947 CDFG survey.

The Fish Fork, Iron Fork, Prairie Fork, and South Forks of the San Gabriel River have

also contained resident rainbow trout and been planted with hatchery rainbows since at least

1930.

Topanga Creek Drainage The CDFG electrofished Topanga Creek in mid-November 1979 (D. P. Drake, CDFG,

unpubl. memo. of 4 February 1980). Flow was intermittent at this time, and habitat quality was

variable. O. mykiss was present, with individuals ranging in length from 10 to 32 cm. Twelve

trout measured from 25 to 32 cm, but apparently no young-of-the-year (trout <10 cm) were

found.

Keegan (1990b) concluded that Topanga Creek had a relatively high potential for

steelhead restoration, based on observed flow, substrate, stream morphology, and riparian

conditions. The stream’s high-gradient aspect, and a wide beach at the stream mouth, may result

in steelhead passage problems under low flow conditions. Adult steelhead were reportedly

present in pools upstream of the lagoon in March 1990. Swift et al. (1993) also indicated that

steelhead have run in Topanga Creek in recent years.

Various Smaller Coastal Drainages The CDFG conducted an electrofishing survey of the following smaller coastal drainages

(listed from north to south) in Los Angeles County during mid-November 1979, primarily to

determine the presence or absence of O. mykiss (D. P. Drake, CDFG, unpubl. memo. of 4

February 1980): Arroyo Sequit, Willow Creek, Unnamed stream 0.8 km south of Willow Creek,

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San Nichola Canyon, Los Alisos Canyon, Lachusa Canyon, Unnamed stream 0.47 km south of

Lachusa Canyon, Encinal Canyon, Steep Hill Canyon, Unnamed stream 0.77 km south of Steep

Hill Canyon, Trancas Canyon, Unnamed stream 1.25 km south of Trancas Canyon, Zuma

Canyon, Ramirez Canyon, Escondido Canyon, Latigo Canyon, Solstice Canyon, Unnamed

stream 1 km south of Solstice Canyon, Puerco Canyon, Marie Canyon, Winter Canyon, Malibu

Creek, Unnamed stream 0.92 km south of Malibu Creek, Unnamed stream 2.27 km south of

Malibu Creek, Carbon Canyon, Las Flores Canyon, Unnamed stream 0.35 km south of Las

Flores Canyon, Piedra Gorda Canyon, Lena Canyon, Tuna Canyon, and Topanga Canyon. Fish

were found only in Arroyo Sequit, Malibu, and Topanga creeks (see above). Most of the other

drainages were dry.

Zuma Creek was also dry when surveyed by Keegan (1990b). Lack of stream flow was

cited as the primary factor which would limit steelhead restoration in this stream. In contrast,

Keegan (1990b) concluded that Solstice Creek had steelhead restoration potential because of its

adequate base flow, high invertebrate production, suitable substrate, and intact riparian

vegetation. Its potential could be increased, however, with pool enhancement and removal of at

least two barrier falls.

Swift et al. (1993) indicated that steelhead have run in Mullholland Creek in recent years.

ORANGE COUNTY

San Juan Creek Drainage Steelhead have historically populated San Juan Creek. Juvenile steelhead were collected

from the lower creek by the University of Michigan in the summer of 1939 (Swift et al. 1993).

Adult steelhead were reported, and resident rainbow trout and/or juvenile steelhead, were seen in

a CDFG survey of the stream in 1946. Hubbs (1946) reported an anecdote regarding angler

catches of steelhead in the San Juan Creek estuary. The lowermost 3.2 km of the creek are

channelized for flood control, at least one major migration barrier exists in the lower creek (see

below), and water is diverted from the stream. Apparently, 1969 was the last year adult

steelhead entered the creek (Woelfel 1991), and the population is currently considered extinct.

Rainbow trout stocking records for San Juan Creek dated back to 1941.

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More recently, plans for a fish passageway (Hinson 1989), at the downstream channel

stabilizer at Calmat Lake in lower San Juan Creek, have been approved by the CDFG and

implemented (M. Giusti, CDFG, pers. comm. of 13 May 1992). In addition to facilitating fish

passage, the baffled culvert structure is also predicted to sustain a base flow in the lower creek

during runoff periods, thus enhancing steelhead movements to and from the Pacific Ocean.

The CDFG files contained information on resident rainbow trout in the following

tributaries to San Juan Creek, but made no mention of steelhead. Wild rainbow trout were

observed in Falls Creek by CDFG personnel. Rainbow trout were present in Hot Springs

Canyon Creek during a 1946 CDFG survey, and rainbow trout stocking records dated back to

1943. Wild rainbow trout were seen in Trabuco Creek in 1946, and rainbow trout stocking

records dated from 1942 to 1975. Holy Jim Creek, a tributary to Trabuco Creek, is managed as a

catchable rainbow trout stream with stocking records dating back to 1949.

Santa Ana River Drainage CDFG fish sampling surveys in 1951 and 1955 in main stem sections of the Santa Ana

River below Prado Dam produced no fish, although warmwater species were thought to be

present. In 1957, the CDFG indicated that steelhead had occurred in the Santa Ana River

drainage but that they were no longer found there; however, resident rainbow trout were still

found in mountain headwaters (R. R. Bell, CDFG, unpubl. file letter of 16 October 1957; see

also Swift et al. 1993). Flow in the lower Santa Ana is composed primarily of effluent from

water treatment facilities except during the rainy season. Because of this, in addition to

restricted releases from Prado Dam, fish occurrence in the lower Santa Ana is limited (C.

Marshall, CDFG, unpubl. file letter of 30 August 1984). Nehlsen et al. (1991) listed the native

Santa Ana River steelhead stock as extinct.

Among the mountain headwater tributaries mentioned above, Santiago Creek, which

originates in the Santa Ana Mountains, is highly managed for a resident rainbow trout fishery.

Rainbow trout stocking records for this stream dated back to 1943. In Silverado Canyon Creek,

a tributary to Santiago Creek, no fish life was observed during a 1952 CDFG survey. Rainbow

trout were observed in Ladd Canyon Creek, a tributary to Silverado Canyon Creek, when

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surveyed in 1948. Note also that other Santa Ana headwater tributaries in Riverside and San

Bernadino counties also support both cultured and wild resident rainbow trout (see e.g. Deinstadt

et al. 1990).

SAN DIEGO COUNTY and BAJA CALIFORNIA

Otay River Drainage Behnke (1992) citing Barnhart (1986) stated that steelhead occurred in the Otay River,

which enters the Pacific Ocean just north of the Baja California border. No other reference to

historical steelhead use of this river was discovered. The dam at Lower Otay Reservoir currently

blocks steelhead access to the upper drainage where spawning and rearing areas presumably

would have occurred. If a steelhead population did indeed occur here, it is now extinct.

Resident rainbow trout may still persist in perennial headwaters, such as Pine Valley Creek (see

Swift et al. 1993), formerly a tributary to the Tijuana River via Cottonwood Creek.

San Diego River Drainage No formal records of steelhead use were discovered for the San Diego River, although

steelhead were reportedly caught there by anglers (Hubbs 1946). The lower river is now

channelized for flood control, and steelhead access to historical spawning and rearing areas

farther upstream is blocked by the dam that forms El Capitan Reservoir. Nehlsen et al. (1991)

listed the native San Diego River steelhead stock as extinct.

Resident rainbow trout may still persist in perennial headwater tributaries to the San

Diego River above El Capitan Reservoir, such as Boulder Creek (see Swift et al. 1993). Cedar

and King creeks have received CDFG plants of hatchery rainbow trout.

San Dieguito River Drainge Hubbs (1946) mentioned the report of a potential steelhead catch by an angler in the

estuary of the San Dieguito River. No other reference to historical steelhead use of this river was

discovered. Dams at San Dieguito Reservoir and Lake Hodges currently block steelhead access

to the upper drainage. If a steelhead population did indeed occur here, it is now extinct.

The San Dieguito River below Lake Hodges has received CDFG plants of hatchery

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rainbow trout, as has Black Canyon Creek, a tributary to Santa Ysabel Creek (thence San

Dieguito River).

San Luis Rey River Drainage No formal records of steelhead use were discovered for the San Luis Rey River, although

steelhead were reportedly caught there by anglers (Hubbs 1946). The dam that forms Lake

Henshaw reduces the downstream river flow, and blocks steelhead access to the uppermost

portion of the drainage. The native San Luis Rey steelhead stock is extinct (Nehlsen et al. 1991),

although resident rainbow trout persist in headwater tributaries such as Pala and Pauma creeks

(Behnke 1992; Swift et al. 1993).

The main stem San Luis Rey has received hatchery rainbow trout, as have tributaries

such as Pauma Creek (CDFG, unpubl. file records; see also Behnke 1992).

San Mateo Creek Drainage San Mateo Creek was at one time an important steelhead-producing stream in San Diego

County to the extent that it supported significant local sport fisheries of both juveniles and adults

(e.g. Hubbs 1946). The steelhead-producing capacity of the stream, and thus the population, are

now greatly reduced as a result of habitat degradation. The following account on the history of

the drainage and its steelhead/rainbow trout fisheries is based on Higgins (1991) and Woelfel

(1991), except as otherwise noted.

According to local newspaper articles from March and May of 1916, the

steelhead/rainbow trout population in San Mateo Creek was larger and consisted of larger fish

than in neighboring Orange County streams. Fishing success was apparently high. Woelfel

(1991) assumed that these descriptions included catches of both adult and juvenile steelhead, as

well as resident rainbow trout. In May 1939, the Univeristy of Michigan took a sample of

juvenile steelhead/rainbow trout from the San Mateo Creek lagoon and about 13 km upstream

for its zoological museum collection (see also Swift et al. 1993). The local CDFG warden

reported to Hubbs (1946) that steelhead ran consistently in San Mateo Creek, and that he had

personally observed the runs for 20 years. Apparently, adults were as large as 9 kg. The

steelhead run was under annual observation by the CDFG at that time, and juvenile steelhead

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rescues were made. For example, on 7 August 1939, the CDFG rescued about 9,800 steelhead

from isolated stream sections and planted them in the San Mateo Creek lagoon. The CDFG also

observed marines rescue juvenile steelhead from desiccating pools in the Camp Pendelton

section of the creek in May 1946. About 3,100 hatchery rainbow trout were planted in the creek

by the CDFG during 1945–46.

Woelfel (1991) also interviewed local residents and retired CDFG personnel who

provided a variety of anecdotes based on their personal observations made between 1900 and

1950. Descriptions of adult steelhead included visually estimated lengths up to 76 cm and

weights up to 7 kg, although most recollections were of fish <50 cm in length. These anecdotes

also gave an impression of the variability of stream flow in the creek system, and how juvenile

steelhead/rainbow trout survived summer drought conditions in isolated pools; fish losses

occurred in some cases when water temperature and dissolved oxygen became too high and low,

respectively. Steelhead/rainbow trout, including adult steelhead, were also observed in the San

Mateo Creek tributary, Devil Canyon Creek.

The headwaters, from 1.6 km above the Devil Canyon Creek confluence to just below a

waterfall in the upper drainage, was surveyed by the CDFG in October 1950. Apparently, there

was no continuous flow in the creek from the mouth to the headwaters. Bedrock pools and

basins provided habitat in which juvenile steelhead/rainbow trout could survive until winter rains

created continuous flow conditions again. Natural reproduction had been successful that year

based on the observation of young-of-the-year trout.

There were fewer observations of juvenile steelhead/rainbow trout in San Mateo Creek

after 1950. Trout were found from the lagoon to the headwaters at Los Alamos Canyon during a

CDFG survey on 1 September 1979. Woelfel (1991) reported anecdotes of juvenile

steelhead/rainbow trout presence in pools in the upper drainage during the early 1980’s, and of a

few steelhead adults around 50 cm long being captured by a local resident in the lower creek in

1986. However, no juvenile steelhead/rainbow trout were found in San Mateo Creek by Woelfel

during surveys in 1987 and 1988.

The San Mateo Creek steelhead population was probably reduced periodically by natural

episodes of sediment input from within the watershed. However, increased groundwater

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extraction in the lower creek area since the mid-1940's is responsible, both directly and

indirectly, for the inability of steelhead to use the system as they have historically (Lang et al.

1998). Riparian vegetation has been lost, stream channel width has increased, and surficial flow

has been eliminated during most of the year. Thus, the migration corridor for immigrating adult

steelhead and emigrating smolts has become very unreliable. Recent human-caused fires farther

upstream resulted in large sediment inputs which filled in pools and the lagoon, both of which

are important rearing habitats for juvenile steelhead/rainbow trout. Fish faunal surveys in San

Mateo Creek in 1995, 1996, and 1997 failed to detect the presence of steelhead/rainbow trout

(Lang et al. 1998).

Nehlsen et al. (1991) classified the San Mateo Creek steelhead population as extinct.

While we agree that conditions in the lower creek system, as described above, have made the

creek less conducive to anadromy than it was prior to extensive groundwater pumping and

development, the CDFG recognizes the upstream spawning and rearing areas as functional for

steelhead production, and that they are still used when sufficient flow allows passage of

immigrating adults (CDFG 2000).

San Onofre Creek Drainage San Onofre Creek is contained within the boundaries of Camp Pendelton. A local CDFG

warden reported to Hubbs (1946) that steelhead ran consistently in San Onofre Creek, and that

he had personally observed the runs for 20 years. The adult steelhead in San Onofre Creek were

apparently smaller on average than those observed in nearby San Mateo Creek, the latter of

which is a larger stream (Woelfel 1991). In CDFG field notes from 1950, Fletcher Creek, a

tributary to the north fork of San Onofre Creek, was described as a steelhead nursery stream.

Rainbow trout and/or juvenile steelhead were present in San Onofre Creek during a CDFG

survey on 1 September 1979. Groundwater extraction and associated effects have probably led

to the extinction of the San Onofre Creek steelhead population, as at San Mateo Creek (see

above).

Santa Margarita River Drainage Higgins (1991) presented a description of the Santa Margarita River as part of a report on

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a steelhead recovery assessment. The lowermost portion of Santa Margarita River is contained

within the boundaries of Camp Pendelton where much of the river flow is diverted into O’Neill

Lake, the water supply for the camp. Impoundment and diversion of river flow begins in the

headwaters, however, at Skinner Reservoir and Vail Lake. With groundwater pumping also

occurring, there is no surficial flow in the lower river during much of the year. These conditions

were exacerbated during the 1987–92 drought.

Few details were discovered regarding the history of the steelhead in the Santa Margarita

River. In May 1939, the Univeristy of Michigan took a sample of juvenile steelhead/rainbow

trout from the lower river for its zoological museum collection (Swift et al. 1993). Adult

steelhead may have ascended the Santa Margarita River into the 1970’s (Swift 1975 as cited in

Higgins 1991). In 1980, Camp Pendelton increased the height of the diversion at O’Neill Lake,

which probably created a complete barrier to immigrating adult steelhead. In addition, water

quality in the river decreased during 1970–80 because of pollution inputs from several sources.

Erosion has apparently increased in the watershed; as of 1990, much of the river bottom was

silted, and the depth and area of the lagoon were reduced. No steelhead spawning habitat exists

below the diversion dam at O’Neill Lake, so several successive years of unsuccessful

reproduction has apparently led to the extinction of the population (Nehlsen et al. 1991). The

CDFG planted hatchery rainbow trout in the Santa Margarita as recently as 1984, but Higgins

(1991) saw no evidence of a naturalized population resulting from these plants. De Luz Creek, a

tributary to the Santa Margarita, has also received CDFG plants of hatchery rainbow trout.

Santo Domingo River Drainage The southernmost extension of the historical steelhead range in fresh water is most often

given as the Rio Santo Domingo in northern Baja California, Mexico (Moyle 1976; Barnhart

1986; but see Behnke 1992), based on the work of Needham and Gard (1959). Collecting

expeditions to the Rio Santo Domingo took place during 1936–38, and as of that time, steelhead

still reportedly entered the river from the ocean during periods of high runoff in winter. A more

recent publication about the status of, or conditions for, steelhead in the Rio Santo Domingo was

not discovered, although resident rainbow trout are still known to be present in the drainage

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(Behnke 1992).

Sweetwater River Drainage Nehlsen et al. (1991) listed the native Sweetwater River steelhead stock as extinct. No

other reference to historical steelhead use of this river was discovered. The dam forming

Sweetwater Reservoir in the lower river currently blocks steelhead access to the upper drainage

where spawning and rearing areas presumably occurred. Stream flow is also impaired farther

upstream where Sweetwater Falls Dam creates Loveland Reservoir. A steelhead population

would indeed have difficulty persisting in the Sweetwater River under current conditions.

Resident rainbow trout may still persist in perennial headwaters such as Cold Creek (see

Swift et al. 1993), a tributary to Green Valley Creek (thence Sweetwater River). Green Valley

Creek has received CDFG plants of hatchery rainbow trout. Small juvenile steelhead/rainbow

trout were seen in the Sweetwater tributary, Noble Creek, by the CDFG in 1946.

Tijuana River Drainage A CDFG warden in San Diego County reported to Hubbs (1946) that, in about 1927, he

had seen two adult steelhead that were taken by anglers in the lower flowing portion of the

Tijuana River. No other reference to the historical presence of steelhead in the main stem

Tijuana River was discovered.

However, there was mention of steelhead in the report of a mid-1930’s CDFG survey of

Cottonwood Creek, a major Tijuana River tributary in San Diego County. Apparently, the native

juvenile steelhead/rainbow trout population had been successfully supplemented with CDFG

plants of both resident rainbow trout and juvenile steelhead. Steelhead access to most of the

Cottonwood Creek drainage was blocked by the dams forming Barrett Lake and Morena

Reservoir. The Cottonwood Creek tributary, Kitchen Creek, has also received CDFG plants of

hatchery rainbow trout.

It is assumed that the Tijuana River in Mexico has been developed for water resources

and otherwise degraded, as seen in San Diego County steelhead streams, thus blocking steelhead

access to upstream spawning and rearing areas. Because no reports suggest otherwise, the native

steelhead population in the Tijuana River drainage, including Cottonwood Creek and its

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tributaries, is considered extinct.

OVERALL TRENDS FROM

DRAINAGE-BY-DRAINAGE ACCOUNTS The history and current status of steelhead were reviewed for 91 coastal drainages, comprising

276 streams. The information for 177 main stem streams and primary tributaries was used as a

subsample for further analysis (Table 4). The steelhead stock in each stream was conservatively

assigned one of four status ratings, based on professional judgement of available information

(see footnote 2 in Table 4 for an explanation of each status rating). The availability of reliable

data on juvenile sizes, densities, and adult sizes; the known presence of wild resident rainbow

trout; and the stocking history of juvenile steelhead and rainbow trout, were determined on a

drainage-by-drainage basis. In addition, a combination of documented evidence and

professional judgement was conservatively applied to identify each of nine man-related factors

that has negatively impacted the steelhead population size and persistence in each stream.

Overall, steelhead are present, without any discernible, significant change in production from

historical levels, in 14% of 168 streams for which a status rating could be assigned (Table 5).

Assignment of this rating to a population was usually based on the persistence of habitat quality

through time. In another 31% of these streams, steelhead are present but production is clearly

reduced from historical levels, or likely so, based on the nature of the impacts on the production

area. In many cases, these reductions are extreme and include populations which are often

referred to as remnants of historical runs, and are near extinction (e.g. Salinas, Carmel, Santa

Ynez, Ventura, and Santa Clara rivers and tributaries, and Malibu Creek). Steelhead are extinct

in about 24% of the 168 streams where they occurred historically, and the current presence or

absence of steelhead is not known in the remaining 32%. The latter category may well include

several extinct populations in degraded streams where surveys have not been conducted for

many years. Reliable estimates are lacking with which to describe steelhead population declines

in actual numbers. However, estimates of historical average annual runs were 20,000 adults for

the Santa Ynez River, 4,000–5,000 in the Ventura River, and 9,000 in the Santa Clara River.

The current average annual run in these rivers is probably <100 adults each, which indicates that

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populations in the highly impacted southern counties have declined by at least two orders of

magnitude.

Various trends were revealed when the status data were considered on a latitudinal

continuum, with counties or county groups serving as data blocks (Table 5). For example, the

proportion of streams in each county with steelhead present at or near historical levels varied

significantly, and generally decreased from north to south, while the proportion of extinct

populations increased over the same gradient (Fig. 17a; Table 5 for Χ² statistics for among-

county differences). The proportion of extinct populations ranged from 0 in San Mateo and

Santa Cruz counties in the north, to 0.92 in the Orange/San Diego county block in the south.

Within the latter block, the Tijuana River steelhead stock was included as extinct, while that in

the Santo Domingo River was classified as unknown, due to a lack of information regarding

contemporary steelhead use of the stream.

The proportion of reduced populations also varied significantly among counties, and

generally decreased from north to south (Fig. 17b). The average (± SD) proportion of remaining

but reduced populations was greater in the four northern counties (0.38 ± 0.12) than in the

blocks representing the five southern counties and northern Baja California (0.13 ± 0.12). This

pattern reflects the fact that, on average, a greater proportion of streams in the southern blocks

was already reduced to extinction. The proportion of streams for which status was not known

did not vary significantly among county blocks (p>0.05; Table 5).

The proportion of streams in each county block planted with exotic strains of hatchery-reared

steelhead varied significantly (Table 5), and while there was no clear latitudinal trend (Fig. 17c),

the proportion ranged from 0.52 in San Mateo County in the north to <0.10 in the Orange/San

Diego county block in the south. Overall, 25% of the 177 streams analyzed received plants of

hatchery steelhead. The proportion of streams in each county block planted with hatchery

rainbow trout also varied significantly (Table 5), and generally increased from north to south

(Fig. 17c). About 35% of streams reviewed were stocked with hatchery rainbow trout, and the

frequency reached 80% in the Ventura/Los Angeles county block.

About 35% of 165 steelhead populations reviewed were negatively impacted by water

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diversions. Frequencies varied significantly among counties, although there was no clear

latitudinal trend (Table 5). The proportion of steelhead populations affected by water diversions

in San Mateo County (0.37) approached that of some of the southern county blocks (Table 5),

because of both domestic and agricultural water demands. The proportion of streams in each

county block containing dams that lack functional fishways also varied significantly (Table 5),

and generally increased from north to south (Fig. 17d). Overall, 24% of the 165 populations

reviewed were negatively impacted by the presence of dams in the drainage. The proportion of

streams in each county block, where the quantity and quality of spawning and rearing habitats

for steelhead were reduced by siltation, varied significantly (Table 5), and generally decreased

from north to south (Fig. 17d). Nearly half the steelhead streams reviewed in each of San Mateo

and Santa Cruz counties were affected by silt inputs. Siltation of streams in San Mateo, Santa

Cruz, and Monterey counties was most often associated with logging operations, where steelhead

production was also negatively impacted by the effects of logjams and slash in the stream

channels (Table 5).

The proportion of streams where channelization eliminated steelhead habitat varied

significantly among county blocks (Table 5). Even though there was no clear latitudinal pattern,

the proportion of channelized streams in the Orange/San Diego county block (0.27) was higher

than in all county blocks to the north (≤ 0.08).

The proportion of streams where steelhead populations have been negatively impacted by

barriers and pollution did not vary significantly among county blocks, and no latitudinal trends

were apparent (Table 5). Overall, 18% of 165 streams reviewed had barriers, and 10% were

affected by pollution. Barriers included impassable culverts and bridge support structures, for

example, but not logjams and dams, the frequencies of which were analyzed separately. Natural

barriers, such as bedrock falls, were also not included because they are natural components of a

river system that influence the distribution and abundance of steelhead and resident rainbow

trout.

Finally, the proportion of spawning and rearing tributaries to which steelhead access has

been blocked by main stem impediments (e.g. dams, major diversions) varied significantly

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among county blocks (Table 5). The overall proportion among 165 streams reviewed was 0.21.

No latitudinal pattern was evident; instead, the results reflect the fact that steelhead are no longer

able to reach important upstream reproduction and nursery areas in most of the major coastal

river drainages south of San Francisco Bay (e.g. the Salinas, Carmel, Santa Maria, Santa Ynez,

Ventura, Santa Clara, Los Angeles, San Gabriel, Santa Ana, San Diego, and Tijuana river

drainages, among others).

DISCUSSION This review has clearly demonstrated the precipitous decline of California steelhead in coastal

drainages south of San Francisco Bay. Assuming the 168 main stem streams and primary

tributaries used in the status analysis were a representative subsample, steelhead populations are

either extirpated or reduced in size from historical levels in at least half the steelhead streams in

the study area. The status of nearly another third of the populations reviewed could not be

determined based on available information; some of these populations are also probably reduced

or extirpated. Only 14% of the streams reviewed still had steelhead present where there was no

discernible, significant change from historical production levels.

Nearly all historical steelhead populations are extirpated in Orange and San Diego counties.

The effect of these extinctions is that within a few decades, the known southern limit of

steelhead in North American fresh waters has shifted northward from the Santo Domingo River

in northern Baja California (Needham and Gard 1959), to Malibu Creek in Los Angeles County.

Local extinctions continue to creep northward (Fig. 17a) and are concomitant with urban

expansion and an increasing human demand on freshwater resources. Indeed, among the

developmental activities negatively affecting steelhead populations, water diversions were

proportionately most common overall (0.35), and especially common in the San Luis Obispo

(0.44), Ventura/Los Angeles (0.40), and Orange/San Diego (1.00) county blocks (Table 5).

Dams were often present in conjunction with water diversion, especially in larger drainages, and

were third most common proportionately among the factors affecting steelhead abundance and

persistence (Table 5).

The 1976–77 and 1987–92 droughts certainly exacerbated unfavorable conditions for

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steelhead in streams where water resource development had already impacted the populations.

Steelhead in the study area, though, have evolved with periodic drought cycles as part of long-

term climatological conditions. However, the relatively recent and drastic increase in human use

of water is rendering an increasing proportion of these steelhead production systems

dysfunctional, or nearly so, and populations are disappearing.

As documented in the drainage-by-drainage status accounts, the Santa Ynez River drainage

is among these dysfunctional systems. Santa Ynez steelhead runs were on the order of 13,000–

25,000 adults prior to the construction of Bradbury Dam in 1953, and the beginning of an

intensive water management program in the lower river area. The steelhead population declined

to a remnant by the late 1980’s, which prompted the California Sportfishing Protection Alliance

(CSPA) to petition the California Fish and Game Commission to list the Santa Ynez River

steelhead as an endangered species under the California Endangered Species Act (R. J. Baiocchi,

CSPA, petition of 25 August 1989). The basic tenet of the petition was that the Santa Ynez

steelhead was a unique subspecies or strain of migratory rainbow trout because of the maximum

size of 9 kg attained by adults caught in the past, and because of the estimated magnitude of the

historical runs.

Following the recommendation of its staff (E. Gerstung, CDFG, unpubl. memo. of 22

November 1989), the CDFG in its official response to the CSPA (P. Bontadelli, CDFG, unpubl.

memo. of 7 December 1989) rejected the petition based on the conclusion that these

characteristics were not uncommon in California winter steelhead populations. The CDFG

recommended instead that it would be more appropriate to reformulate the petition to encompass

all southern California steelhead populations because of similar life histories (presumed short

freshwater residence as juveniles, protracted ocean residence during droughts), and similar

problems with regard to availability and quality of freshwater habitat.

This approach was pursued by Moyle and Yoshiyama (1992) in their synopsis of supporting

information for listing of “southern steelhead” as endangered or threatened. Southern steelhead

were roughly defined as being ecologically and physiologically adapted to the seasonally warm

and intermittent coastal streams from San Luis Obispo County and southward. The authors

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indicated that the line of demarcation was vague, due to a lack of detailed knowledge regarding

southern steelhead life history, physiology, and genetics, and that the distribution of southern

steelhead could reach as far north to include Monterey County steelhead as well.

Let us now take an even broader spatial scale and consider the potential uniqueness of

steelhead for the entire coastal region south of San Francisco Bay. These populations are unique

from a zoogeographic standpoint simply by virtue of the fact that they represent the

southernmost portion of the native steelhead range in North America, which extends as far north

as the north side of the Alaska Peninsula (Burgner et al. 1992). Coincident with this aspect is

that these populations inhabit a unique continuum of stream environments, one completely

different from any found north of San Francisco Bay. This continuum consists of a gradation of

streams originating in the relatively moist and cool coniferous forest-dominated drainages in San

Mateo and Santa Cruz counties, to streams southward that are dominated by arid chaparral and

grassland landscapes not usually associated with steelhead.

This collection of populations is also unique from at least one key life history aspect in that

smolting and emigration to the ocean at age 1 becomes the norm, at least in main stem

population segments (c.f. Life History Analysis). Smolting at this relatively early age for

steelhead is most likely a consequence of one or both of the following. First, because smolting is

a function of an individual salmonid’s physiological performance (Thorpe 1986), which we

measure as growth and express as size/age, steelhead in central and southern California coastal

drainages are able to develop as smolts by the end of their first year because of overall higher

average annual water temperature and a longer growing season with regard to photoperiod. Both

temperature and photoperiod are basic determinants of growth rates in fishes.

Second, smolting at age 1 may have also been selected for as an advantageous life history

characteristic, especially in smaller streams with unreliable stream flow during late summer and

fall; with emigration to the ocean, the instream mortality risk due to stream desiccation is

eliminated (Borgstrø m and Heggenes 1988; Titus and Mosegaard 1989, 1992). The trade-off is,

of course, that ocean survival of age 1 smolts may be lower than that of the larger age 2 smolts,

presumably because of the greater predation risk experienced by smaller individuals. When

263

present, some fish also spend their second year in the lagoon or estuary of a stream system

before smolting and emigrating to the ocean (e.g. Jones & Stokes Associates 1986; Smith 1990).

The significance of small, intermittent tributaries as steelhead production areas has not

always been appreciated. The CDFG conducted stream surveys to locate planting sites during

the expansion of their catchable trout management program, beginning in the 1930’s but

especially after World War II. In the stream survey files for Santa Barbara County and

southward, it was often noted that small headwater streams lacking perennial flow were

unsuitable habitat for catchable trout. Because these small streams had no apparent fishery

value, applications to develop their water resources were seldom protested. When dams were

proposed, the loss of wild resident rainbow trout and steelhead was mitigated by the opportunity

to develop warmwater reservoir fisheries, which was in a major experimental phase during the

post-war period (Jenkins 1970). The use and importance of seasonally intermittent streams for

spawning of both steelhead (Everest 1973) and resident rainbow trout (Erman and Hawthorne

1976) were not documented until much later. It is known now that, in dry years, newly-emerged

fry escape mortality by moving downstream to permanent water in the main stem, but remain in

the tributary in wet years when stream flow persists (Everest 1971; Erman and Leidy 1975).

Considering the hydrological variability in steelhead streams south of San Francisco Bay,

some populations probably experience major reductions approaching extinction during drought

cycles, and then rebuild again by an influx of founder individuals from other populations during

normal and wet years. For example, only 14 adult steelhead returned to the Carmel River fish

ladder during the 1991-92 season following 6 successive years of extreme drought. But

hundreds of adults returned during the very wet 1992-93 season. It is likely that this run

included individuals spawned in other drainages, as an abundance of adult spawners would not

be expected after several years of poor recruitment.

The pervasive view on the spawning migrations of anadromous salmonids is that a very high

proportion of adults home strictly to their natal stream to spawn (e.g. Taft and Shapovalov 1938).

Although this strategy may work well in regions where streams are typically stable, it may not

be selectively advantageous where access to the natal spawning and rearing area may be highly

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Under natural conditions, where the effect of periodic drought on population persistence is

not exacerbated by human extraction of water, steelhead/rainbow trout populations probably

seldom go completely extinct, even in southern California. Except in some very small first-order

coastal streams lacking perennial refugia, at least a fraction of the resident component of the

unpredictable because of stochastic meteorological conditions. The degree of homing in

steelhead south of Santa Cruz County has not been explicitly studied. However, it has been

suggested, for example, that adult steelhead in southern California may tend to be larger and

older on average than elsewhere in California because frequent droughts may prevent them from

entering their natal stream during their first year(s) of maturity (E. Gerstung, CDFG, unpubl.

memo. of 22 November 1989). Basic research questions on this problem should ask whether it is

more advantageous under such conditions to simply delay spawning and resorb the gonads if

unable to enter the natal stream (winter steelhead are ripe upon entry to fresh water), or to simply

enter any accessible stream in the region and proceed with spawning. It can be argued that the

risk of mortality and not passing on one’s genes is greater if the energetic investment in gonad

production is made in one or more successive years but spawning is not completed, than if entry

is made into an, albeit, “unfamiliar” and therefore riskier reproduction area, but spawning is

completed and progeny may be produced which can carry one’s genes to the next generation.

A body of concepts and models has been consolidated recently under the rubric of

metapopulation dynamics (Gilpin and Hanski 1991) that provides a framework within which this

general problem may be approached. Broadly put, a metapopulation is a set of local populations

that interact via individuals moving among populations (Hanski and Gilpin 1991). The

metapopulation concept is related to MacArthur and Wilson’s (1967) theory of island

biogeography in that there are two essential elements in common: extinction and (re-

)colonization. Island biogeography represents one extreme on a continuum where the mainland

population (the source of colonists) is immune to extinction while the surrounding island

populations are not. Theoretically, all populations in the set comprising the metapopulation have

a risk of extinction which is dependent on the size of the habitat patch and thus the population.

Most real world metapopulations appear to fall between these opposite ends of the continuum as

based on empirical evidence (Harrison 1991).

265

population, as well as juvenile steelhead which fail to escape to the ocean, probably persist

through drought cycles, as evidenced in the drainage-by-drainage material reviewed herein.

What leads observers to the conclusion that a population is truly extinct is the absence of adult

steelhead spawners in the stream because of blocked entry. The presence of resident rainbow

trout had been identified in about 36% of the populations listed in Table 4; their actual frequncy

is probably much higher but simply not explored and documented.

A related aspect with regard to persistence, especially in small streams with small

populations, is the significance of life history variation (see Life History Analysis). This

characteristic has probably been the saving grace for steelhead, considering the highly

unpredictable conditions under which they exist throughout much of the study area.

Representatives of each generation may potentially be present in both fresh water and the ocean,

which reduces the risk of extinction from direct mortality. Resistance to extinction from reduced

heterozygosity and associated effects of inbreeding in small populations is enhanced by the

presence of overlapping generations in the spawning population (Saunders and Schom 1985).

This is facilitated by (i) the presence of mature male parr or a full resident-population component

in fresh water; (ii) variation in steelhead age at emigration; (iii) variation in steelhead age at

maturity; and (iv) repeat spawning among steelhead (see Titus and Mosegaard 1992 for a related

example). The interchange of individuals among populations in a metapopulation would also

help maintain genetic diversity.

RESEARCH AND MANAGEMENT RECOMMENDATIONS In conclusion, the following recommendations are made to assist in the development of future

research and management programs.

Relative to several other salmonid species, little is documented about steelhead mating

systems. The composition of spawning aggregations should be studied in the field, and the

proportionate gametic contributions of all male forms, including mature male parr, should be

determined. The frequencies of mature female parr should also be investigated, and the

relationship of these individuals to the migratory component of the population determined.

266

The genetic and/or environmental determinants of individual life histories should be explored

by following individually marked fish through time and space. One specific research question is

whether mature parr remain in fresh water after spawning and functionally assume a resident

life-style, or if they eventually smolt and leave the stream to continue growth in the ocean, and

return to spawn again as large migrant spawners. Life history information at the population level

is also lacking over much of the study area; for example, mean smolt and sea ages, and the

relative survival rates of different smolt-age groups to first spawning.

Management activities should be directed toward the conservation of both the resident and

migratory forms of the species within a stream or drainage. For example, minimum stream flows

should maintain growth conditions that allow for the development of the average natural

frequencies of all physiologically-based life history characteristics, such as smolting and parr

maturation. As discussed earlier, life history variation appears to be important for steelhead

persistence in a number of ways.

ACKNOWLEDGMENTS We would like to thank Mr. Dennis McEwan, Mr. Steve Parmenter, and especially Ms. Jennifer

Nelson, all of the CDFG, for their assistance in information gathering, particularly in CDFG

regional stream survey files. We would also like to thank Dr. Jerry J. Smith, San Jose State

University, Mr. Mark Capelli, Friends of the Ventura River, Mr. Allen Greenwood, San Diego

Trout, and many others (list under construction) for their inputs of data, reports, observations,

and commentary on various drafts of the manuscript. Preparation of this paper was supported by

funds from the Agricultural Experiment Station, Department of Forestry and Resource

Management, University of California, Berkeley; and by Interagency Agreement No. FG1384

with the Stream Evaluation Program, Environmental Services Division, California Department

of Fish and Game.

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Table 1 (in prep). Summary of adult steelhead angler catch statistics from early 1970’s creel census’ on the

San Lorenzo River, Santa Cruz County. Source: CDFG data.

282

Table 2. Estimates of adult steelhead run size in Arroyo Grande Creek, San Luis Obispo County, based on

interviews of local landowners and anglers (from R. N. Hinton, CDFG, unpubl. file report of 1 March 1961).

Winter season(s) Estimated no. of adult steelhead in spawning run

1939-40 and earlier 500–5,000 annually

1940-41 3,000–5,000

1941-42 through 1948-49 <200 annually

1949-50 200–300

1950-51 through 1953-54 <100 annually

1954-55 100–200

1955-56 300–500

1956-57 <100

1957-58 100–300

1958-59 <100

1959-60 <100

1960 through 1 March 1961 0

283

Table 3. Summary of steelhead captured in lower Santa Clara River system by Puckett and Villa (1985).

Capture date Adult Smolt Capture method & site

2 Apr 1983 Male, 61.5 cm FL, 2.0 kg, age 1/2* — Hook & line, Sespe Creek

4 Apr 1983 — Potential steelhead, 15 cm FL Fyke net in Sespe Creek

26 Apr 1983 Spent female, 70.4 cm FL, 2.95 kg, age 1/2 — Weir in Sespe Creek

mid-Mar 1984 c. 61 cm — Hook & line, Sespe Creek

17 Mar 1984 Dead female, 45.0 cm FL, age 2/1 — Weir in Sespe Creek

21 Mar 1984 — 15.7 cm FL Fyke net in Sespe Creek

23 Mar 1984 — 17.8 cm FL Fyke net in Sespe Creek

* Age A/B: A = no. years in freshwater, B = no. years in ocean.

Fig. 1. The study area, comprised of coastal California south of San Francisco Bay, and northern

Baja California, Mexico.

Fig. 2. Variation in (a) mean smolt age (·) and mean sea age at maturity (_ ), and (b) mean adult

length, as functions of increasing latitude among steelhead populations from central California

(Waddell Creek) to southern British Columbia. Data are from Withler (1966) where mean ages at

smolting and maturity are calculated as in Fahy (1978).

Fig. 3. Mean (± SD) monthly upstream (a) and downstream (b) migration of adult spawners at

Waddell Creek, Santa Cruz County, 1933-34 through 1941-42. Data are from Shapovalov and Taft

(1954).

Fig. 4. Total age frequency distributions of male and female steelhead spawners at Waddell Creek,

Santa Cruz County. Data are from Shapovalov and Taft (1954).

Fig. 5. Frequency distributions of (a) ages of male and female steelhead smolts, and (b) sea ages of

male and female steelhead at first spawning, at Waddell Creek, Santa Cruz County. Data are from

Shapovalov and Taft (1954).

Fig. 6 (in prep). Mean (± SD) monthly downstream (a) and upstream (b) migration of juvenile

steelhead at Waddell Creek, Santa Cruz County, 1933-34 through 1941-42. Data are from

Shapovalov and Taft (1954).

Fig. 7. Negative density-dependent relationship between stock (estimated number of eggs produced)

and recruits (estimated number of first-time spawners) for steelhead at Waddell Creek, Santa Cruz

County. Data are from Shapovalov and Taft (1954).

Fig. 8. Positive relationship between the age of steelhead at initial downstream migration at Waddell

Creek, Santa Cruz County, and the proportion in each age-class surviving to return from the ocean as

first-time spawners. Data are from Shapovalov and Taft (1954).

Fig. 9 (in prep). Juvenile steelhead population structure at Gazos Creek, San Mateo County.

Source: unpublished CDFG file data.

Fig. 10 (in prep). Juvenile steelhead population structure at San Pedro Creek, San Mateo County,

the northernmost steelhead population in the study area. Source: unpublished CDFG file data.

Fig. 11 (in prep). Length-frequencies of angler-caught adult steelhead at the San Lorenzo River,

Santa Cruz County. Source: CDFG data.

Fig. 12 (in prep). Steelhead spawning run at Scott Creek, Santa Cruz County, 1908–1940. Source:

CDFG egg-taking data.

Fig. 13. Total estimated number of adult migrant spawners at Waddell Creek, Santa Cruz County,

1933-34 through 1941-42. Data are from Table 35 in Shapovalov and Taft (1954).

Fig. 14. Structure of (a) the resident rainbow trout population in the upper portion of the Big Sur

River tributary, Juan Higuera Creek; (b) the mixed resident rainbow trout/juvenile steelhead

population in lower Juan Higuera Creek; (c) the predominantly juvenile steelhead population in the

mainstem Big Sur River, Monterey County, in November 1992. Data are from Titus (unpubl. data).

Fig 15 (in prep). Length-frequency distribution of adult steelhead returning to the Carmel River,

Monterey County. Source: CDFG data.

Fig 16. Juvenile steelhead population structure in (a) the perennial creek portion and (b) the lagoon

of the Arroyo de la Cruz, San Luis Obispo County, during late summer–fall 1981. Based on

unpublished CDFG data.

Fig. 17. The proportion of streams in each county block with (a) steelhead present with no

discernible change in production from historical levels (·), and steelhead extinct (_ ); (b) steelhead

present but at reduced levels; (c) hatchery steelhead planted (·), and hatchery rainbow trout planted

(_ ); and (d) dams (·) and siltation (_ ) affecting steelhead abundance and distribution.